i use sp systems core cell as its the best core i can get,ive tried loads of others but this stuff is the nuts.i use epoxy and various grades of glass cloth . i dont bother with inserts in these as if the wind warrants foot straps ill be on this
nice shape you got going on there fella ,
hope it comes out nice for ya.
if you do want inserts nsi do surf pads with built in inserts