Looks a bit like it UncleSamSwiss.
There are a few Linq bits in the codebase but you should be able to reimplement them when you come to compile for 2.0. In fact it seems that there are three and it look like all be commented out to no great effect.
throw new NotImplementedException();
So just change the project type, remove the FX3_5 symbol, make those few changes and hopefully that'll then work.