As long as he's eating it, and the food bulge is gone before the next feeding, I'd say you're fine offering the larger prey. However, since 40g is ~23% of his body weight, I wouldn't feed any more frequently than 7-day intervals. If you try to feed more often, he'll likely start skipping meals, have extra large defecations (which means he's pooping nutrients instead of using them), and have a higher risk for regurgitation (since he will always have food in him when you handle him). Oh, and feed him what makes him healthy - if you want a big snake, get something other than a male BP.