It looks good, but then again, you'd have to drop someone. So say you drop Wally. You obviously lose out on three's. Gil's great for them, and wally and MoPete are on the same level. So you lose out on threes. Gils also great with steals, but he's not a TON better than MoPete, and Wally's not really a factor. Scoring you probably stay the same with Bosh/MoPete equaling Gil/Wally. But you really gain on rebounds and FT%, as well as FG%. Blocks don't really do anything either way.
In the end, I think you have to pull the trigger. Bosh is a legitimate first rounder, and MoPete's definately right in the 6-7 round. Plus you need a center, because you only have two (unless Bosh is eligible). So I say do it and drop wally. He's an injury risk anyways.
Btw, how many teams are in your league. Because that team is stacked.