[B. W.]

the R4 will run 134a fine. Many GM's ran the R4 after the mandated switch to R134a.

Here's what I'm going to use:
stock GM serp belt setup - 95 K1500
stock R4 compressor
stock hoses off of the compressor (has manifold that bolts to compressor, high side hose to condenser, low side hose coming from accumulator)
stock pipe from evaporator to condenser (this pipe houses the orifice tube) May need to shorten/lengthen for proper fitment/routing (or just build one)
stock orifice tube
square body evaporator (haven't tried to install, a member here posted that he'd installed one & if fit)
universal condenser ( forum member posted he used P/N CNFP 1427 from Ebay (14" x 27") Cant go much taller than 14" , hood latch assembly is in the way

Unknowns -
accumulator - need one with the outlets in the correct orientation. Looking for a stock GM application. need pre-'96 (switched to metric fittings in '96)
there are also some stock GM adapter pipes with various curves to connect the evap. to the accumulator ( one possible P/N 15551630)

I have one for a '98 GM truck that mocks up nicely but the threads are metric (option- install metric end on low side hose to compressor & build adapter pipe from evap. to accumulator)

Will need to fab lines from condenser to stock high side hose coming from compressor & outlet of condenser to pipe with orifice tube (or just build hoses, there are many manifold configurations available for the R4, check Murray Climate Control)

Anyway, it can be done nice & clean and look almost stock. It will take some custom work. Many of the parts are stock GM parts making availability/replacement easier ( & maybe cheaper)

If anyone knows of an accumulator that works post it up please!