A/C high and low pressures for coldest air

[dgl6y6]

ive found lots of descriptions about how to do the conversion but nobody mentions what pressure to charge the system to.
can anybody shed some light?

[zookeyknee]

Dont mess with the high side press. The low should be between 40-60 lbs A better way is superheat method simply slowly add refridgerant slowly til the low press lines start to sweat water condensate where it exits blower box assy back to the condenser next to the radiator.I switched my 87 bll over to 134 only changed low side adaptor got good starter refridgerant with O ring conditioner A stop leak additive plus system oil in it mines going on two yrs no leaks no problems just Ice cold air.