My opinion: increase compression by milling the head. It is a little labor intensive, but the "best bang for the buck". It is the only mod that does not have a down side. Increases power and fuel economy, both. Of course, while the head is off, you might want to consider a valve job, depending on condition of the head. If you have a valve job done, you might want to consider oversize valves. And so forth and so forth. That is what is called project creep. I am serious about milling the head if you are limited on what you can do.
PS: you can buy a cam for Between $75 for a regrind, and $140 for new. But a cam without compression increase is a waste of money.
