Take your head to a machine shop and have themm do a three angle valve job and reseat and check the valves.
have them check and re-knurl or replace the valve guides and valve seals.
With the exception of the valve seals the above stuff you can't do without the machine shop.

If all you want to do is replace the valve seals and maybe the valve springs you can do that if you have a valve spring compresor.

Just a note: valve seals are just oil control, they have nothing to do with loss of compression. The valve seat is where compression is lost.