Sorry to bother y'all but I couldn't find anything that addressed this question.
I'm building a project from 2012, the code was written then for an Uno. Can I assume that it will run OK on a current version Uno, or should I try to find an older one?
Will run ok. May have to tweak the start of the code a little to get it to compile with the later IDE.
Check the release notes from -0023 to 1.0 and later:
(scroll down to about 1/2 way down the page)
The hardware will be fine no matter what.
Thanks, very helpful 
I installed the 1.6.5 ide, opened the .pde file, hit Verify/Compile and got:
Done compiling.
Sketch uses 6,038 bytes (18%) of program storage space. Maximum is 32,256 bytes.
Global variables use 477 bytes (23%) of dynamic memory, leaving 1,571 bytes for local variables. Maximum is 2,048 bytes.
No error messages so I guess it's time to get some hardware...