[Nireez]

You can do a quick leak down test in the head if you want but dude, just take them off and get them redone. Have the valve seals and lifters installed and just dish out the extra cash for the gaskets. It will be completely worth the hassle if there is any valve damage. Think what you would do if you got it all back together and you go to start it and you got valve damage. You would be cursing yourself for not doing it while the engine was out. If the belt is already off the car, there is no way to check timing. If you put the belt back on, it will show perfect on the marks.

To answer your question, you won't be able to tell by the valve springs if you have damage. You can pull your intake and exhaust manifolds off and peak in there but you can't tell too much because if there is damage it won't be much considering the car was not running when the cams slipped.

AGAIN, if that was mine or a HUGE majority of the people on here, I would pull the heads off, check the valves, shave the head, install new seals and 99 lifters and put them back on.