The original street and OEM "race" cast grey iron hemi blocks where used in both top fuelers and funny cars until Donovan and Milidon came out with cast aluminum blocks in 1971 or so.
I'm sure all of those old motors far exceeded 2500 HP even back then on nitro fuel work
On your deal I wouldn't worry at all up to or over 1500 HP with a good tune twocents

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)