Moving to a GM based platform in top sportsman is almost the no-brainer these days - especially when you can buy a complete 1325HP - 632 for around 37K or so carb to pan - at some point beating your head against the wall hurts! I got a close look at the version -2 of the 600-13 heads that Sanders had done and the all of extensive welding and custom machine work that went into them - they were exceptional and unique pieces ! - the real kicker is you can get a set of equally prepared GM based heads that will out perform them for probably less than half the cost. Then again what runs in top sportsman in division 3 - seems you need 1600+ hp just to qualify into the field.