a few engine swap issues

I am replacing my olds 307 with a chevy 350. I've run into a few issues and would like you guys input.
1. Cruise control
My mechanic said that I cannot use the 307s cruise control since it is computer controlled. Is this correct? If I can't use the 307s cruise control, what other options do I have?
2. Distributor
My mechanic said I can use the 307s electronic advance distributor, but it would not advance. He said the distributor won't advance above 3k rpms (or so) like it should, but that since you don't go much above 3k rpm in daily driving, it would work ok.
3 carb
My mechanic said I also can not use the 307s carb. He recommended I buy a basic 600 cfm edelbrock carb from the auto parts store as opposed to buying a used quadrajet.
Does anybody have any thoughts or advice?
4. Rear main seal
My motor, while made in 1987, is an 19xx-86 style. The 2 piece rear main seal, at this point, does not leak at all. Should I have him replace it (not cheap, and would be stretching the budget) as a preventative measure? I've heard these wear out and start leaking at approx 150k (but thats just what I've heard). The donor truck had 115k (I think) on the odometer (only has 5 digits (read 15xxx), and the motor is way too strong to be 215k). If the rear main seal starts leaking, is this catastrophic (if I keep adding oil)? Maybe I'm just being overly worried about this (not yet a) problem?

distributor is different,.

the cruise should just be a cable hooked to the throttle linkeage,.


an old 350 would be easier,.