sounds like more than a prop problem with that low of performance, is your tach correct? engine running on all 8?
I had an 88 211 Libby that had a mildly built 300 HP small block that only ran low to mid 50s GPS, mine ran best with a Ballistic prop but your heavier.... it did have that built in hook from the factory like most of these hulls(more like a built in trim tab)
after you determine if your engine is ok try any stainless 4 blade you can get your hands on, Rev4, Bravo, Mach
I still have the Ballistic if your interested
I had an 88 211 Libby that had a mildly built 300 HP small block that only ran low to mid 50s GPS, mine ran best with a Ballistic prop but your heavier.... it did have that built in hook from the factory like most of these hulls(more like a built in trim tab)
after you determine if your engine is ok try any stainless 4 blade you can get your hands on, Rev4, Bravo, Mach
I still have the Ballistic if your interested