big block question

[BigBlocksRule]

I'm with these guys.
Getting into a decent aluminum head for a reasonable price on a budget only gives you a couple of choices, both Chinese castings that will cost more to get set up right than buying a good head to start with.
Your operating range dictates which port to use.
A set of small port (peanuts) with a good valve job and a little bowl work will make tons of torque from just off idle to around 5500rpm's with headers only. Don't use a factory peanut port intake, the ports in the intake are more restrictive than the head - and that's in spots that you can't reach with a die grinder. Use an intake made for large ovals and open the head ports up to match it and continue that for about an inch into the port. Then you'll have the intake velocity that promotes good cylinder filling ang big torque.
If you want to turn it higher, find some 781's or 049's, stock valves with the same bowl/valve job and a good oval port intake. You'll lose a little bit of torque but she'll pull hard to well over 6K.
I'm a roller guy myself, haven't built a flat tappet engine in years. One flattened lobe will cost you a lot more than the conversion now. All the tiny metal particles will end up in your bearings, so they'll all have to be swapped out. Crank will need a polish, too. Plus your down time. You can use a Gen 6 cam and retainer since all big blocks have the boss on the front of the block, it'll just need to be drilled and tapped if it's not already.

If this engine is going back into the camper special, I'd stick with the small port heads.