I have a complete buggy and am starting a rebuild.

I dad the motor running a few years back and it ran fine up and down my 1/4 mile dead end road, but I want to make this thing street legal and decided it was best to completely go through the motor.

I have been reading that the H5 cases are weak. It would be great to get a little more HP than stock but it is equally important to try to stay near the budget on this. This will just be a summer toy, won't be drag racing or anything (the look on the face of a "sports car" owner getting passed by this would be pretty sweet though )
There are some decent hills in the area, and not having to crawl up them would be good too.

Don't have my plans set in stone, but I was thinking at the very least to go to 1600cc pistons, dual carb setup, electronic ignition and better exhaust.

Will the case be ok with a little more than stock HP?

The case will be fine with slightly more than stock. Your plans are fine.

Thanks guys!  Based on the replies I will keep with my plans to use 1600cc pistons, and continue to use the 1500cc heads.  I know the compression will go up a little, but sounds like I should be ok.

Trying to get this thing drive-able as inexpensively as possible and can determine desired upgrades after running it for a bit!