Spyder 1997 Eclipse GS-T Spyder build advice

[Phosgene]

I was recently sold a automatic 97 Eclipse GS-T Spyder with a blown engine from a friend for $250, he claims it is due to walmart lube service refilling the engine with trans fluid and from what i have seen, this does appear to be the case from what i can see. It has been sitting in his yard for several years and there is a dead raccoon in the passenger side floorboard, the top seems to have leaked some and the clear coat is separating from the metallic brown paint. I have several other cars and just plan to keep this one as a beater and possibly enter it in chump car at some point, here are some of my ideas and concerns about it.

I plan to swap in a 4G64 block, and use the 4G63 heads and turbo, I understand that in order to do this that i will have to block off some oil ports and use a different timing chain, but i need to know what years of 4G64s are the best to pick since i will be pulling one from a junkyard? Also, are the engine mounts and bellhousing the same on all 4g63/4g64 blocks so that it will mount correctly in the eclipse?

Im my state (GA) i need to pass emissions which is simply an OBD-II Check Engine light test, which is very easy to pass but i dont know if a ECU tune will effect this, and what ECU tuning options are available for the 97 Eclipse that are inexpensive and maintain OBD-II compatibility?

I have a set of spare 225/60/16 tires that i plan to have mounted on the car, how much will this effect the speedometer due to the tire diameter change?

 

[Silver gryffon]

Consumer Reports says that 98 and 01 are the most reliable and that 97 and 99 are the least reliable.
As far as tire diameter, the gst came with 16s.

 

[AlwaysSunnyOhio]

I think he's asking about the over all aspect ratio of the tire. Since these cars came with 55 instead of 60's.

Overall diameter of the tire is what will affect your speedometer.

 

[Kevin4G63]

http://www.tacomaworld.com/forum/tirecalc.php

Use this site to calculate the difference in speed