A/C Conversion to R-134?

[mac88chp]

Has anyone here ever done or have an R-134 air conditioning conversion on their car? The original R-12 system on my '88 CHP has been in-op for about as long as I've owned it and I'm considering having the conversion upgrade to R-134 done prior to taking the car to Las Vegas in April. I'm especially interested in what visual differences will be apparent underhood afterwards and if anyone has any advice on the process and results and a fairly recent cost figure.

Thanks!