I finally got a chance to take my car to the shop to get the A/C system charged and converted to r134. The total came out to $285 and he didn't do a leak test yet but said that if it seems to lose charge to bring it back. The price break down is below. I don't really know if I was over charged but the cost seemed reasonable.

Labor: $112.50 (at $75 an hour)
Parts: $151.28

Refrigerant- $30 (5 cans x $6)
A/C Receiver dryer- $59
O/Ring- $1.50
Rrigi/Tracer Oil- $17.90
Retro Kit- $28

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1983 300D (parked for four years)
2012 VW Sportwagen TDI Manual
2001 Miata SE
1962 Chevrolet Corvair Rampside