“Max effort daily driver” 318 build vs “Budget” 400 swap

one thing i haven't seen mentioned is what resources you have available to you. is obtaining parts (shipping) a concern? do you have a good machinist for the rebuild work?

is the 400/727 complete? if not are parts easily available to you? it would really eat into your budget and morale to have to track down all kinds of parts and then get relentlessly rung up on shipping.

at a minimum you're going to be in for mounts, an oil pan, cutting the driveshaft, exhaust, maybe some wiring work. you may also need to address the cooling system and possibly power steering (i didn't see if you mentioned it was equipped).

you also said that you plan to drive the car like a grandma 99% of the time. so it would seem like the ultimate goal isn't all out power?

personally, i'd go the path of least resistance. you already have the small block, there are recipes to make an honest 400hp with a 318. you already have some of the peripherals-- headers, intake, etc.

my recommendation would be to build that 318 out