[marco]

Hi James,

If your engine is completly disassembled you could consider bringing it to a professional company to have it washed inside and outside.

Otherwise I would advice for the old handwork with wire brushes and scrapers.
All openings should be plugged because loose wires migh come off the brush and fly around.
Murphy's Law says that these wires will fly in that particular opening you forgot to plug.....

Degreasing the porous cast iron blocks is time consuming, you should repeat this a couple of times to get the surface degreased sufficiently for a good paint job.

Red oxide primer is perfect for the job.
2-pack primers give perfect results also but are more expensive.

Sandblasting is far to powerfull, the blast will most likely damage your "plug-work" with desastrous results.

Best regards,

Marco