Most people today use a Sanden compressor for retrofits. You need brackets that match your engine (only you know what that is). Several companies make them (search here). One is Bouchillon Performance I recall. Brackets for a slant six are rarer. I got them cheap off a Volare slant w/ a Sanden compressor mounted. For a cheapie approach, plumb to an under-dash unit, either a vintage used one or new (~$100 ebay). Vintage and Classic Air systems are not cheap and they sometimes leave the customer to work it out.