We have a barrow that weighs 268 lbs with 14 days til show. In the past 11 days, he has gained 38 lbs on 2 lbs 611, 0.75 lbs Heavyweight, 0.75 lbs oat groats, and 4.5 gr Paylean twice a day. How can Inslow him down without crashing him?

That is 7 lb of feed plus Paylean. I would expect that kind of gain or more. So, to gain 12 lb in 14 days that calculates to 0.86 lb/day.

I suggest feeding:
(Total daily feed; divide into 2 equal meals):
High Octane Fitter 35. 2 lb
High Octane Fitter 52. 1 lb
High Octane Depth Charge. 1/2 lb (8 oz)

The Fitter 52 will do what Paylean did previously but it will not cause extra weight gain.