A/C REBUILD w/R-12

I just rebuilt the motor in my 1989 R3500 (still a square body) and I'm planning to re-install the A/C system. I was on the fence about this for awhile but decided to go forward since it gets pretty hot where I live.

Here is where I am so far:

I have flushed the condenser and evaporator well. Clean and dry.

Already purchased: new dryer/accum - AC DELCO replacement, pressure cut-off switch

About to purchase: new hoses and lines, new orifice tube, and of course all new o-rings. Lastly - a new compressor.

I have access to R-12 and a guy who can do the filling. I'm told it's better to go this route if one can but then again I'm no expert on this so that's why I'm here.

A. Will all new/reman compressors that are available function properly with R-12? Are some better than others? I am bracketed up for the old Harrison type v-belt (short body) and would like to stay with this configuration unless there is a compelling reason to go with something different.

Will the orifice tube that I purchase as a direct replacement part be configured for R-12? or will these work for both systems?

The hose assembly and accumulator line seem readily available from multiple suppliers. Any best choice advice? Same with o-ring brands.

Lastly, oil. Any brands better than others?

Thank you in advance for your responses.

Might consider looking into a parallel flow condenser; they're generally more efficient than the tube and fin type that came in these (R12) trucks. GM transitioned in the 90's along with the R-134 switch (I think).

The R4 compressors seemed to be hit and miss on reliability these days, but I've used them in the past with success. I've purchased AC Delco from Advance Auto and that jungle website and neither lasted. If you're leaning towards the R4, Four Seasons may be worth a shot.

Some notes from my install here.

To my understanding, R-134 requires a different type of barrier hose vs. R-12. As to oil, Ester is designed to work with R-12 or R-134.

I bought hose, fittings, and o-rings from coldhose.com and made my own.

It's really not an issue using R12 just need the correct orifice tube, cycling switch and confirm correct oil is in compressor if any. Today's hoses and o rings will be compatible.

Agree with previous post on compressor quality. A new R4 lasted a total of 50 hours before it started leaking around the case. I lost 2 charges of R12 before finding the source. For that reason might be better options today that last and preform better.

You will not notice a difference in performance using R12 or R134a. These systems were so oversized to begin with. Don't overthink it. I have converted hundreds on systems over the years. Just evacuate the system, drain as much oil as possible and add R134a compatible oil.

In your case just buy the parts and if you have access to R12 and will continue to have access then use it. If not, just charge with R134a now and not have to worry about it down the road if there is an issue.

Are you sure you have an R4 compressor? My '87 has a DA6.

Have you already bought the compressor? A sanden style compressor would be a nice upgrade, they are more efficient.