Use em. Just do as Will states above. Check valve to bore clearance before buying a higher lift cam. The shrouding that Steve states is real but, on that thing, the compression gain will do more good than the "harm" that the shrouding will.
We ran 061`s on a 68 350 back in the day with a 3 something duration Crane cam. 390 gears. Back then, that car won it`s share of street races. `68 LeMans, N50/15 tires with a 2800 stall. Car did have a fiberglass front cap.
