Yah, it’s lower compression and a 73 340 which only had 245hp. A small cam upgrade and headers might add 30 at the most. I stand but my original estimate. The OP does t really know anything about the build.
245 hp is net hp, when talking built hp most are talking in dyno trim, which at very least is no accessories best tune, generally headers. Most engines in dyno trim are at least 30 + hp gross above net.
25 degrees ain't a small cam upgrade, generally we consider about a 5 degree bump as the next size up that's 5 cam sizes larger. I'm sure there's more aggressive 235 cams that would do even better.
A low cr 318 with a 218 cam and 4 bbl in dyno trim does 282 hp, I'm sure a 340 with better heads, intake and 17 degrees of more cam gonna do a lot better.