To make a long story short, a person that owes me money runs a local salvage yard. They have a fairly picked over 1997 Miata that I get to take parts off of. I've already claimed the seats which are in much better shape than mine, some 15x7 borbet wheels which will probably end up on my civic, and pending whether it has a torsen or not, the rear end and neccesary parts.
Now on to the questions.
My miata a 91, has the vlsd. It seems to help, a little. If the 97 doesn't have a torsen should I still grab it? From what I understand, the torsen differential itself will drop in, so down the road I could upgrade. The 4.10 gears would help my gas mileage a little, and the larger ring gear is a good thing.
The car has 97,XXX miles on it, the motor can be mine if I want it. Now the wrench in the gears, I have a MSPNP that is going in soon on my 1.6, can I run the 1.8 easily on the 90-93 megasquirt? What else do I need to swap the motor? And finally is swapping the early BP worth it? My car has a E36 M3 load of miles on it but the motor itself is only at 60-70K miles, I kind of enjoy the peaky nature of the 1.6, but some more lowdown grunt never hurt. Given that the motors would more or less put out the same power, is the unknown commodity and work of dropping it in worth it?

