I am new to small blocks, but the guy that sold it to me said that it was a stock 360 LA with only a .484 Purple Shaft and gear drive. It ran 7.548 to 7.56, the last time out, for 9 runs. It is running full exhaust w/ headers.
Ok. It's probably pretty low compression then. Like Moper and FlyFish I like NGK's and the R5671-7 FlyFish recommended should do you good. Proper plug reading is essential to gettting it dead on of course.