If he doesn`t know how much oil is in the engine, if it was me, I would drain the oil, measure how much oil came out, and then dump the oil in again. There are numerous deep sump oil pans, some are much deeper than stock, others have widened sumps, if you knew the depth and width of the oil pan sump, that would help. On my 59s 428, I am running a deep sump Canton oil pan (straight sides, no "kick outs"). My pan is listed as a 7 quart pan, and I am using a stock replacement 428 CJ dipstick and tube, and I run 6 quarts in it, which puts the CJ dipstick at the "Add 1" mark. Not all dipsticks are the same length, or have the same markings on them.