I am looking to replace a 2 ton condenser and air handler, with a condensing furnace, coil and outside condenser, inside equipment moved a bit from 1st floor closet to a kneewall attic above. Tieing into existing ist floor ductwork in crawlspace below (equipment itself cannot be located below 1st floor by code)

I have 2 proposals and waiting on a third (for a month despite my followups) but none of them address my noise concern with any specifics. I know what many will say, but believe me getting a proposal is like pulling teeth in my area, let alone one with any specifics or, God help me, an actual load calculation....... The new location will be virtually on top of the Return Air intake..... maybe a foot of vertical duct and a 90 degree turn, filter, then into unit with blower right there at return opening. Because of some of my reading here, I mentioned my concerns but didn't get any specific answers, I'd like to agree on some minimum standards in the contract that can help, like duct lining. Still such a short run concerns me. Is there anything else I can do? I don't see how return can be lengthened as often mentioned due to location unless they installed the furnace vertically using a kind of reverse of the typical return drop (Meaning upward, entering top of downflow furnace) instead of the seemingly more natural horizontal position spanning the return and supply duct.

Are there 2 or 3 things I can specify that typically can help with return air noise from such a close blower motor? (Return air opening will be adequate size so the speed of air through grill won't be the offending issue)

Could it make sense to actually orient the install like I mentioned. I'm sure they will have their own thoughts on that but I want to be as specific as I can to alleviate the noise issue not realize an unacceptable problem until startup