You will have to lift the cylinder head and look at what has been broken.
It can be a breakage of piston segments, or rupture of valve seals in butt.
In the checkbook, the camshaft can be removed with the cylinder head and with the help of a useful, release the valves of its semiconos and casserors to change the unopened cooking seals, but ...
1º is fucked
2nd 2nd you need to have experience so as not to shit it (it is very easy to shit it)
3º You run the risk that this is not the breakdown and in the end I have Cylinder wear, it is not going to have a step of the ostia and have to rectify or change motor for wear.
All the best.