Jacob,

You can do your own 134a conversion. fcpgroton.com has Volvo's 700 conversion kits and as I recall there are good instructions on the process in the 700/900 FAQ. Kits for 700's are generally under $100
You didn't mention what year 700 you have but here's a link to 87-90 conversion kits.

http://www.fcpgroton.com/VolvoAC/volvo760b280.htm

I converted my 88 240 to 134a last summer, that kit requires an evaporator and runs more than twice the cost of the 700 kit. But filling the system with 134a at 2 dollars a can sure beats $45+ per can I was paying for R-12. Cooling in my 88 is now pretty good for a 240, even with 134a in the system. The 700 conversion should be simpler, less costly and produce even better results. I plan to convert my 87 745T to 134a this spring. I found an auto A/C parts supplier who rents vacuum pumps by the day, so once the old system has new seals,dryer, ester oil etc. I'll draw it down and refill with 134a myself. Since the system leaked all the old R-12 out years ago there's no need for R-12 recovery equipment and to involve the sometimes unpleasant folks at an A/C shop. Hope this helps

>Where is the high pressure test port on the compressor? I found what I thought >was the cap for it but I couldn't get it off.

There is none.

>I did look at the low side pressure. Temp outside was 65, low side pressure was >sround 40psi at idle, dropping down to 26 psi at sustained 3k rpms. Outlet temp >was approx 42 at idle dropping down to 39 when revving the engine. Does this >sound right?

Yes.

>If I decide to go whole hog with this, evac the system, new receiver and >orifice, etc, is the compressor rebuildable? Is that something that I can do or >should I just buy a rebuilt compressor?

What's the problem?