Peninsular with possible freeze damage

[twomey]

My mechanic installed a new starter on my 1995 Peninsular 6.5L. It now barely turns even with new batteries. He thinks it froze up last winter. The coolant and oil both look good. No leaking from the block.

Few questions:
1. Should an off the shelf starter work with the Peninsular ?
2. Is there a definitive way to tell if the engine suffered internal damage ?
3. Is it possible to upgrade to a used/reconditioned Yanmar ? (with the EPA rules)

Thanks,
Tim