350 TBI to 454 swap

[Pano]

I have read a lot of threads and decided to replace my good running 350 with a 454 to better tow my 27 ft camper. I considered the 8.1 but with the additional cost and fuel delivery complications I decided the 454 would be easier and pull the trailer fine. I have an 87 V2500 with a TBI 350, TH400 and 4.10 Rear end. It is a 4x4 with a NP208.

I figure it is best to find a donor vehicle to get the radiator, alternator, PS pump, shroud etc.

if I get a pre 87 non TBI is it an easy to convert the TBI to carb?

If I stay TBI how far forward can I look for a donor vehicle and when will I need to consider a newer computer or other issues?

I have been searching and found 90s RVs and PUs with both options.

Thanks