Be it right or wrong here's what i did:

SC degreaser, scraper and a small wire brush - nearly 2 cans. i found that the pressure pack works reasonably as a spray after loosening up the gunk.

POR15 Marine Clean, then Gerni blast got it almost clean now, a bit more with the wire brsuh in stubborn places, then repeat the POR15 and gerni had it well prepared.

Then to etch, I used POR15 'Metal Ready', and according to directions washed off. it showed itsepf to be clean and ready for paint. Air blast crevices and water trapped parts and I left it in the sun for a few hours to be baked dry.

Masked up the clutch housing and other parts not to be sprayed and then used a spray can of the selected colour from the Winnabey chart (close match) from S-Cheap for $15.99 and proceeded to empty the can on the engine.

Happy chappy with the result.

Again, thanks for all contributions and advice. I hope this thread helps others.

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..still waiting for the Italian Job sequel to see if the bus went down