most cost effective swap?

[chance]

M30 isn't that hard at all. Need custom mounts, custom exhaust, and a jumper harness if you don't have an m20 car.

Doesn't get much easier that that.

[e30construction]

i wanna m30 2 lol..what car does the 3.5 ltr m30 come in?

[VinniE30]

M20 2.7 turbo vs. M30 vs. M5x vs. M60 vs. LS1

Which setup do you think is the most cost effective way to go as far as the amount of power output and reliablity goes?

Or if you have a better one tell us.

Since you mentioned reliability I would rule out the turbo right away.

The M30 is cheap to buy, cheap to swap in, cheap to rebuild, and cheap and very easy to maintain, even moreso than an m20. In stock form you will have 208HP and around 220-230 with a good flowing exhaust and tune.

An M50 is simular to the m30 in costs except more expensive and complicated to rebuild. Around 190HP stock and 200-210 with good flowing exhaust and tune.
M52, S50, and S52 cost more to buy but give more power in stock and modified form, up to 240HP stock for an S52 and around 280 with basic modifications necessary for the swap anyway. But keep in mind, the S52 cost upfront at the very least twice the cost of a simular condition m30, m50, or m52.
I would say the reliability for all these is close to the same as the m30, very good. It depends more on what old wear items you replace on the engine than what kind of engine it is in this case.

Now the M60 and the LS1.
These are both in a completely different ballgame as far as costs go.

The M60 will get you to 300HP with good flowing exhaust which will need to be custom anyway. I know m60 engines themselves are relatively cheap, easily cheaper than an s52. But this swap is way more complicated, time consuming, and more costly overall than an M30 or M5X.

The LS1 gets you more power than the M60 but is just as involved to swap, if not more as the M60, and the engine itself is much more expensive, and the other swap related costs are just as much.

So there's the rundown.
If you want an actual answer to which one is the most cost effective you have to define that somehow. For example additional HP over stock (318 or 325?) or total end result HP (with or without mods and to what extent?) per dollar spend (for the engine itself or total cost of swap? and does this include a rebuilt because most of these engine are 10-20+ years old)..........
I would just do all the research you can on what's involved to swap these and weither you are prepared to do that and make the decision for yourself.