You can swap a 2.6 head on a 2.0 IF it is from a 79 - 81 2.6 from a truck - it will drop the compression 1/2 point. The hot trick in the early days was to use the 2.0 head on the 2.6 to raise the compression 1/2 to 1 point. You may have to get a rubber molding kit from Eastwood to remake that grommet. I have a spare 2.6 head from an 80 or 81 truck, but I haven't looked at it in a while to see if it is any good. If you go for the non jet valve heads, you will have to get a newer intake manifold, as the bolt pattern is totally different, and it would probably fail Cali visual inspection.