I wouldn't worry about the blocks being a stability problem, especially 1". Plenty of trucks run large blocks to lift them (rear axle under the leafs), including my g/f's '71 ford 4x4, which has 4" blocks in the back
. They really aren't that unusual, and as long as they're properly installed you shouldn't have any issues. The pictures below are off of the Gurney car, which, in addition to plenty of other suspension mods, uses blocks to set it a little lower (actually appears to be a block welded to a wedge). As you can see, it spends ALL its time going around corners fast!
I suppose the other question to ask it, what springs is the car running now? Stockers, or aftermarket? If its got aftermarket springs like Super Stocks or ESPO lift springs it could be higher than normal. Got any pictures of how it sits now?
I ask because I currently have a set of XHD springs on my Challenger. They spring rate is great, but the ride height is about identical to the worn out stockers before I swapped them out
. This isn't exactly what I was looking for, so I could probably be talked into parting with them
.