In general, any dense firebrick is likely to be durable and useful in the
feed tube and burn tunnel, where you need abrasion resistance. It can work well in the heat riser if well insulated, but will take longer to come up to full operating temperature and be slightly less efficient. Getting all the MSDS info is always good, but in most
RMH cases not essential.
The ideal configuration if you can choose all the materials is probably dense firebrick splits (1 1/4" thick) to line the feed tube and burn tunnel, with soft insulating firebrick or other refractory insulation for the heat riser and surrounding the hard brick core.