1978 GL1000 cylinder heads vs. 1976 heads

[ntintruder]

I am working on a 1978 GL1000. I checked the compression with a HF tester, got 120 on all four, put oil in all four and tried it again, same results. According to the manual I downloaded, the compression reading should be no lower than 140. Since the oil did not change anything I am assuming that the problem is in the valves. I have a parts engine from a 1976 and the cylinder heads seem good. I took them apart and glass beaded everything, replaced seals, etc. and put the plugs in, turned them over and filled the chambers with lacquer thinner. They didn't leak a drop in two days, so I'm thinking they are good and I was considering using them on the 1978 while I do a valve job. What is the difference between 1978 and 1976 heads?

[dingdong]

The cams are the only difference. The 76 has hotter cams. If you use different heads you should use the original cams.

[Old Fogey]

The cams are the only difference. The 76 has hotter cams. If you use different heads you should use the original cams.

And keep the corresponding rockers. And don't just swap over the complete rocker assembly. The rocker carrier and the head are machined as one unit. Change the original rockers into the other carrier, keeping them in the same order.
http://www.wingovations.com/cams-and-rockers/4579471096

While you're at it, check out the rocker shafts and if you find wear do this:
http://www.wingovations.com/rocker-spin ... 4579471094