[GMC70c20]

The only problem with just adding more power is allot of power plus allot of weight equals breaking drive train components (transmissions, drive shafts, axle shafts). I have a 79 3/4 ton 2wd truck and it scales 4200 lbs and thats with a small block and th-350. In order to get your 3/4 chassis into the mid 13's it would take about 450-500 hp. Now that isn't really allot of power for a 454 but another thing is that much power there's know way its gonna hook with the 3/4 ton setup. It's not really that much work converting it to a 1/2 ton I'm doing it to my 70 now, it would be money well spent. I'm not trying to rag on your truck, hell I have 2 c20's myself but if your looking for performance your better off converting it to a half ton. Here's a little food for thought by just converting it to a half ton you could get it down to 3600 lbs or so, I did on mine and I'm looking at about a 12.10-12.3 1/4 mile with 525hp.