Tunnel ram 440

Ok so I got the tunnel ram going but I ended up getting another engine. 440. With trw flat tops. Compression is around 9.5 to 1. Crane 68051 camshaft that's on a 106 lobe sep. 3000k stall, 4.10 gears, 727 auto. Timing is set at 20 btdc. Now I'm having problems with the carb tuning it will load up at idle and die when put in gear. And likes to backfire through the carbs. Now I just rebuilt the carbs with off the shelf Holley trick kits and I'm thinking the power valves are too big and are probally blown out now. What's an ideal power valve size for the two carbs for a cam with alot of duration and low vacum? Does any one have a combo that worked for them with the two Holley 600 vac sec carbs? Thanx in advance!