the hp is really the big issue with sleeves or your internals for that matter. the issue that comes into play with stock internals and the stock sleeves is the boost level. typically on good tuning a stock lowerend with stock sleeves call safely run 8-10 psi but some guys on here i have seen running what you ask. my recomendation...
if you are going to spend the time building the motor with rods pistons and having it balanced ur halfway there to having a block that can handle high boost...spend the extra 1000 bucks and have the block sleeved. especially if you want to go higher than 10. just not worth the risk if u ask me.