True but they still run and run good. My take is do the swap with lapped velves and new seals and the Hughes spring kit.
Later upgrade cylinder heads.
LA's are all okd and need seat and guide work by now also so in my mind that's a wash between LA and magnum engines.
This was my exact plan until I checked to see if the valves were sealing...which they weren't. Not even close. Part of the problem is that the stock exhaust seats are not really hard at all. Combine this with lean running efi and you're screwed.