Irvine 1.3's?...They tend to be pricey-you probably have a better chance of picking up an original on Ebay-where they appear reasonably frequently-as do Indian ones....use that, in the model, and keep a weather eye out for an Irvine popping up somewhere by chance (most are in collections....!)-they weren't made for that long and in my opinion way overpriced when new-about 90 pounds-when you could buy an Irvine 40 for about 50 pounds at the time. A classic case of killing the goose that laid the golden egg-had the price been more reasonable, they would have sold a lot more.

ChrisM