After reading this article, this passage in particular stuck out to me,
Has anybody explored the T500 with a pair of Jemcos & expansion chambers to see how far we can take this old hunk? If so, what do I need to dial in? I will gladly do this research when I get the paychecks if nobody has yet."But 'the secret' was adopting a CRD programmable ignition module; then spending hours finding the right curve."