There is no question that the 461-291 heads from the 60s hi-perf engines were old school. BUUUUUUUUUUUUUUUT, with careful re-work, they can, and will, make very good heads!!!!
USUALLY, there is plenty of metal to permit opening up the intake runners several cc's, and the REALLY good old time head gurus can shape them to be very efficient for serious performance.
For a street-performance engine, simply cleaning up the bowls, opening the seats up for 2.02/1.6 valves (on heads that were originally 1.94/1.5), and cleaning up and matching the intake runners/ports will go a long way to make these "old school" heads into good performance heads.
All of the above, WITHOUT doing a full blown port and polish, can be done at a fairly reasonable price and the results will be respectable.
I have a SB400 in my 56 Vette with 462 heads that have had a few "tricks" performed on them to produce an appearance of a REAL early head that performs well.
I carefully ground off the double humps and re-shaped a pyramid symbol on the ends to make them look like 57 power-pac heads. Then, I had extra bosses welded, drilled and tapped to permit installing early valve covers with the staggered bolt pattern.
This really produces an old school look!
ANY head, 69-later or aftermarket, will have threaded holes and flat machined surfaces on the ends of the heads which will be a dead giveaway that they are NOT early heads.