Hello all, I'm new here (as if you can't tell ). I am not a HVAC pro, but a home owner but would like to get some opinions on some plans I had in mind for the future. I am thinking of completely having the ducting and moving the furnace over. I apologize for the long post but think the details are important, so here goes

Details on existing system and house:
The furnace- 80% mid-efficiency Carrier natural gas (58WAV091-14), but its only 5 years old, so it should have plenty of life. House is 1950's with central heat and air, all sheet metal ducting run in the basement parallel the main beam and I believe are original- however here's my (negative) observations so far:

Ducting:
1) The basement already has low ceilings at 7 feet. The HVAC ducts run down the middle of the basement ceiling and underneath that area is 6' 3".

2) The house has reverse flow venting- as in, in most areas the returns are on the exterior walls (uninsulated) and the supply are on the interior walls. The kitchen and bathroom have supply on the wall though. Makes no sense to me why it was done this way originally. I also lost two supply ducts when I had a foyer wall removed, so that area is constantly cold especially next to the front door. When the heater turns off, it seems like it gets cold quick.

3) There are only 2 (one on the furnace/AC itself) supplies on the basement in the ceiling and ZERO returns except the furnace itself. There's a bathroom in the basement that has no ventilation at all. Thus, it's always cold down there.

4) Minor issue but the existing grilles are somewhat noisy- (when I remove them it's quiet), which brings me to:

5) The ducts are an odd size which I read is common for an older house, like 5x8 so it's almost impossible to find grilles for the vents. Which ties along with this- because of their off size, they are placed low on walls, and not the floors, so I have to use them with this ugly baseboard trim.

Furnace:

The furnace and water heater currently vents out a masonry chimney in the middle of the house. Since the house is small, it's taking up valuable room in the kitchen on the floor above and in the basement.

To address these issues:

Furnace:
If I can move the furnace, I can get rid of the chimney, it will allow me to put in more counter space or a wall oven in place. I have a closet I believe I can have run vent pipe up to vent out the roof, it'll just have to be enclosed. I'd also would shrink the utility area and have more space to use as a basement. Which brings me to:

Ducts:
1) Since the furnace will be moved to a corner, having the Supply and return ducting run down one side of the basement wall (without basement windows) instead of the center as you see in most homes. This way, a soffit or wall can be built, I won't lose the vertical space, instead horizontal space which I have much more of. I have consulted one HVAC company so far and they've said the supply and return ducts can be run in a vertical orientation along the side wall. One place tells me 8" high ducting is standard- but are there any "wide and low" ducts?

2) While this is done change the flow to be "correct" with the supply at the exterior walls (I'd specify floor vents) and return in the interior walls. I was told having floor vents would be best as the air will rise up and it "washes" the exterior wall, so this would address the cold feeling when the heat turns off syndrome.

For the basement have the the proper supplies and returns, supplies down low to allow the heat to rise.

3) The proper load calculations and sizing calculations should be done of the ducts.

4) To move the furnace, a professional will have to capture, extend and recharge the line for the condenser, size and run the B-vent etc.

I've talked to one HVAC company so far and they think I can keep the existing furnace. But they'd "plan for putting in a high efficiency furnace" when the 80% unit dies.

I realize this is going to cost a good bit of money as it's basically installing a complete duct system AND paying for installation of the furnace as I'm moving it, but at least the house is small, and only 1 level (plus basement which is fully accessible) and I'll be using the existing furnace. But it will allow me to have better use of the basement without the low ducts in the way and allow more usable space in the kitchen above and basement and more even cooling/heating.

Is this project I'm planning crazy or is this something that is actually done? I've searched around the internet and can't find too many people looking to move their ducts and furnaces. My other thought is to continue with the current setup and use space heaters or gas stoves/fireplaces for additional heat as needed.

Anything else as a homeowner I should be aware of before I sign on the dotted line?