About this 3D model

I've been playing with a lot of extruder hot end designs, I've been through every design I could put together for 3mm. One common issue is heat dissipation above the nozzle. Whether the filament is getting too hot too high up or the insulating barrel is too hot for the filament block, I wanted to design a heatsink that could fit the most common designs. While I was at it I figured having optional support bolts would help as well. They don't line up with anything that currently exists but that's easily remedied.The intention is for this to be metal cast in an investment process.I'm curious about how much heat it could dissipate if it were just used in PLA form.