Most bang for buck to do with cylinder head?

[dcarchitect]

so the head is off for a blown gasket, and I am sending out to a machine shop for pressure testing, resurfacing, cleaning, and if necessary any valve work.
While we're cracked open, who knows best what the most bang for the buck improvements are to be made with the M42 head while we're at it?
Thanks!
Looking to spend a few hundred; not thousands, its just an old car nowadays.