I obtained a cheap 1990 RS from with an excellent 5.0 TBI and 700/R but the body is in pretty bad shape with rusts and dents. I am getting a near mint 1986 IROC for cheap. But without an engine nor trans, no harness either but everything is intact including T-Tops (was an LB9).

(a) Would you swap the 1990 RS TBI engine /trans plus wiring into the IROC.

(b) Strip the IROC body parts and implement them into the RS i.e. suspension, front end, fenders, etc. and then get it painted??

Which is less tedious and a better choice?

 

It depends on how bad the RS body is and how nice the IROC body is. It also depends on how good your mechanical skills are as opposed to how good your body work skills are. I really can't give an accurate opinion without seeing both cars in person.