ok heres the issue. I currently own a 1984 318i, automatic, and an extra M10. I also own a 1989 325i manual with rotted shell and m20 with low compression..

Choice A
keep m10 with 220,000km in 318i, buy 5 speed swap for $450 and turbo. I already have turbo manifold, 2 ihi turbos and intercooler, parts i have just collected over time.

Choice B
Keep 318i, swap in the 5 speed from the 1989 325i and buy an m20 with approx. 200,000km for sale for $200, which doesn't have wiring harness, but i would be able to use the one from the m20 i already have.

Which engine is more reliable? What would you do and why? I also have H&R sport springs and bilstein sport shocks installed on the 318i which have about 500km on them, so if i swap in the m20 they would need to be what i use because i cant afford to buy new suspension again. This is a huge choice for me, and whatever i decide to do i want to get on with it soon.
I am posting a poll with the options above, keep m10, turbo and get 5 speed or swap in m20 and use parts from 325i I already have.
This is taking forever to decide, i just know either one will be a lot of work and i want to make sure i pick the most logical and best in the long run decision.
cheers guys, please help me out.