273 Mystery Motor

It wasn't uncommon to replace the solid lifters with a hydraulic cam & lifters, retaining the adjustable rockers and using different pushrods. That's how my Commando is set up. But a flat lobe is questionable — a collapsed lifter would seem more likely.

But if you are choosing a new cam, the big question is do you really have Commando high compression pistons? The low compression 2bbl motor can't handle much cam.