I agree with finding another engine, especially if that is the numbers matching engine for your car. It would hold its value much better if you have the original engine in original condition.
Whether you're in another country or not, that's the idea I would shoot for. Just bide your time. Is there really a need for a rush? More often than not, rushed projects don't turn out as good as they could.
Also, I cannot believe the crankshaft argument. Who cares which crank is in it? If you decide to use it, just make sure of which it is and use the correct corresponding parts. A cast crank will support 600 HP with everything balanced properly and using a good quality balancer. People seem to forget that when bench racing.
Weigh it all out and do what's best for YOU. Don't rely on anyone else (including me) to make your decision. No one knows your situation better than you.
I know if I were in your place, I would do everything in my power to preserve that original engine. JMHO.