I looked at the silv-o-lite pistons that matched your description. The silv-o-lit KB228-30 is the closest one I could find to your description. But I am not 100 percent. Silv-o-lite says it 8.8:1 compression with 76cc head and 7cc valve reliefs. it looks like it sits about .020 in the hole on a standard 9.020inch deck height block. If your block was decked this number would be smaller and it would have slightly higher compression. Using a standard Fel-Pro rebuilder’s head gasket with .039 compressed thicknesses and your 63cc heads, it puts your compression at 9.7:1. The Comp Magnum 292H cam you are using recommends a minimum of 9.5:1 compression. But I find it to be on the low side for a recommendation. When I plug your info in to my desktop dyno program it spits out 432 HP and 409 Foot lbs. keep in mind that this is a computer program but it is fairly close for an estimate. It should be within about 5%. So figure 410HP@6500 and 380FTLBS@4500 real world. Not really a bad combo, but it is quite a bit over-cammed. Additionally the carb is a little small for this combo as well. a 750 Holley style or a 750 Q-Jet would be better. The Holley style will make more power and I find them easier to tune, but the Q-Jet will be better to around town driving and provide better throttle response because of the smaller primaries and provided better economy. A smaller cam and bigger carb would make more power. I plugged in a couple of different cams in to the software and by Stepping down 2 cam sizes and going up to a 750cfm carb, my dyno software says the Comp XE274 makes 445HP@6000 and 436ftlbs@4500 for best power. It would also have better street manners and better gas mileage. Poor mileage is one of the first signs of a cam mismatch. Like other posters have stated you would also need a higher stall converter. The stall speed for the recommendation form Comp for the magnum 292h cam is 3000+ stall. For the XE274 cam it is 2200+ so again stepping down in cam size would make it more streetable and provide better mileage. I would not change to a TH350. It has a 2.52 first gear ration and with your 3.42 it would give you a total ratio of 8.62:1. The 4l60 has a first gear of 3.06 and with the 3.42 gears you have a total ratio of 10.46:1 so it will launch harder and with the 25% overdrive cutting down on the final drive ratios would be equivalent to running 2.56 with the th350. So you would have much better mileage on the freeway if it is a daily driver.