Agree with Greg. I've been pulling these things apart since they were new. In my experience they seem to also have a mixture of imperial heads with metric threads, then the odd bolt will have a metric head. Very wierd. I bought heaps of NOS WB bolts in the 80's and 90's too and they were a mixture.
I'd keep the WB inner guards too if you put on a HJ-HZ front. It will allow you to keep the WB washer bottle and carbon canister without too much hassle, although you may have to drill a hole here or there to align with the support panel. I'd also modify the HJ-HZ radiator support to take a WB radiator - takes a few hours with a grinder and spot weld drill, plus a few welds and presto.