I don't see how we can justify giving advice that standard five-arm compact-drive cranks are hard to find. And therefore you need to pay such a large amount for RF Turbines. That's nowhere near being true. e.g., all Shimano CD cranks from 94 to 96 were five-arm with BCD 94/58, such as XT M737. The last time I bought some M737 they were £25 if I recall.
The only thing you need to look at to see if your Specialites will fit is whether they are Shimano pattern - i.e., with the pin that prevents the chain getting caught under the crank arm located between two bolt holes. (Sugino pattern rings have the pin in line with a bolt hole) Note that the Turbine cranks you're looking at are Shimano pattern.
Thanks man, there is a Pin between two bolt holes!!
If you have any crank suggestions, please let me know, I do like the RF Turbines, but they're not very subtle, perhaps a bit 'hardcore' and fat for a skinny steel frame? Not sure, they do look the business though
Do let me know!