A -6 should do the job, unless you are planning to feed big HP.....
Summit has the adapters w/ the screw in retainers for both the inlet, outlet, and the return lines.
5/16 return is 644113 Black Blue is 644110
3/8 filter in is 644123 Black Blue is 644120
Filter out is 640940 Plated
We use a combo of colors to ID the return vs the inlet....
Hot rodding and drag racing since 55
55 Chevy/LQ9 Tyr Fryer
Turbo Buick in the 9's/142mph.