Holly tube shooters

So im about to order my power valve and a few diff sizes of tube shooters... Rite now i got the straight shooters, and might as well replace them with the better tube style..
So its a 70 duster with a 727 with a 2400 stall and 3.55 gears rollin 25" tall tires
Engine is a 360 .060 over with 10:1, 360 heads 1.88in/1.60ex valves (for now) air gap intake, all MSD ignition, .497in/.483ex lift, 235in/249ex duration at .050, and 107 lobe separation, flat tappet cam, with roller rockers, headders, and 2.5" exhaust to the bumper

Any1 got any ballpark idea where to start with the pump shooter size?
It idles about 6" of vacuum and builds up to about 18"