One of the first motors I built and dyno tune on a engine dyno was a 1962 413 M.W. motor for one of Boyd Coddington cars he had sold to one of his customers.
It was a original 1962 Dodge dart M.W. car that had a really bad worn out made up cross ram motor with a standard 413 C body short block that was already .060 over size with a lot of taper and really thin cylinder walls after sonic testing it
I found a 413 truck block and had it bore to 4.250 and had Ross make a set of low compression pistons so I ended up with 9.5 to 1 compression ratio. I had the original M.W. heads worked on replacing all the seats, guides and valves, the seat were really sunk I had Comp Cams make me a custom grind solid flat tappet cam and freshen the carbs and put the factory jetting in the carbs.
That motor ended up making 499 HP after a lot of testing and experimenting with valve lash, ignition timing and spark plug gap and heat range. I was really happy with those results
We made 32 pulls before changing the oil to Mobil 1 synthetic and lost 30 HP due to the intake gaskets weeping through them oil into the combustion chambers a little with the Valvoline straight 30 Wt. oil. I made one pull with the Mobil 1 and oiled all eight spark plugs
I fixed it by doubling up the intake gaskets and wasn't able to put it back on the dyno to find out how much difference that made