Hello everyone, I have a question about tool design for prepreg products. Sorry for my not-so-perfect English and possibly misnaming some stuff

Previously, I was working on a product for which I had CNC milled model, and I used it to make female moulds. The moulds were made of fiberglass + vinyl-ester resin, and the product was fiberglass/kevlar + vinyl-ester resin combination (hand layup, vacuum bagging, curing at room temperature). The weight was a bit of an issue, so I decided to opt for carbon and kevlar prepreg to minimise the final product mass. It was okay, everything was pretty much acceptable, but process upgrades were definitely needed.

As assembling the parts was a bit tricky, I added minor improvements to CAD models of the tools (redefining parting planes, draft angles, using multi-part tools, ...). I have some NECURON 702 blocks in all possible dimensions, and as per everything I was reading, it's a good option so I'm sticking with it as tool material. But, I'm not sure which are tool requirements - dimensions W×H×L, flange dimensions, corner radius,...

My product is pretty simple - slightly concave trapezoid, max. dimensions W=700 × L=450 × H=25 mm.
Which is the tooling block dimension I need and why? I would put roughly 850×600×75 mm, so there's enough flange-room for breather, sealant, bag and everything, but I would like to know how to calculate/estimate more precisely. Also, corner radius 0.5-1 mm or more?

Is there anything I missed?