The older TBI engine and 700R tranny and 231 TCase is easy.
The newer electronic models are very difficult.
There are various designs of Vortec (heads) starting in 1988. The TBI is best for low end torque. The CPI is best for high end HP.

87 Raizer, 4.3V6, Mod TH700R4,231CHD, detroit rear and LSD front, bouncy seats, 2" lift and 32x15 BFG MT tires.