T100 Head Swap (Pre-'67 on '68 T100R)

 I have a pre-'67 T100 "squish" head, with the chamfered chamber edges,
that I would like to use on my '68 T100R. My current head is the
deep-chambered unit 500 head that fits the raised, "high-compression"
pistons. I bought a set of the squish pistons to go with the earlier head
and I'm unsure whether I can use my current tappet blocks, pushrods and
tubes with the older head. The tubes appear to be the earlier tubes, i.e.,
they don't have the castellated top, nor the top with the holes around it.
How can I distinguish my tappet blocks? Any ideas as far as compatibility?

Thanks for the help,
Cheers,
Chris