In reply to # 3161056 by BMC Any carb engine that needs a valve job needs an engine rebuild. An XPAG engine that needs to be rebuilt will be costly. If your going that far, look into the roller cam. If you just rebuild the head, your gong to have a oil burner more often than not and it will do nothing for power.
When my 1600 MGA lost power over a period of a couple weeks, a compression test showed two bad cylinders. I replaced the head, because the valve seats had receded due to unleaded gas. The new head did everything for the power loss. Plus, it had showed signs of oil leakage through worn valve guides. If the compression test indicates a valve problem, I'll definitely do a valve job. If the cylinder walls look good, I'll stop with that. If I had to remove the engine for a rebuild, a different engine would be going back in.