If you've got knowledge, interest or expertise in the relevant areas, then I'd say go ahead. (If I had the time and was close enough to such a project, I know that I'd love to.)
For the Class 60, given it's age, I'd expect less reliance on high-level coding, and more on machine code and control systems / embedded systems design. If you spent your time on 1980s micros writing in BASIC, then you might be out of your depth. If, on the other hand, you'd outgrown BASIC and had started writing your own assembly code, know what's going on inside a NAND gate or a flip-flop, and maybe got in some practice with a soldering iron or an EPROM programmer, then a Class 60 might be up your street.
Newer machines, such as post-privitisation ones, will have more opportunity for the high-level programmer to show their skills. (e.g. the Class 175 run their Train Management System on Windows 2000 Embedded, and I'm sure other contemporary units are similar.)