Boss block needed?

I'm going to be going in a completely different direction then I have right now. I'm wanting to build a 351w based 427. Goal is 500rwhp. My question is whether or not a boss block (or dart) is needed? Basically if I can save the $2k for the block that would be nice.

This is the current combo I'm thinking of beyond the 427 internals:
90mm accufab TB
90mm SCT BA2800 MAF (already have from current combo)
42 lb injectors (already on current combo)
Ported 58cc GT40X heads (on current combo)
EFI Spyder intake
Long tubes
Custom ground cam
255lph fuel pump

If anybody has any opinion on that combo I'd love to hear what you think about it.

-Dan

BTW, since I'm new. This is what the car looks like.


and this is with the new wheels (I know super rare FR500's)

I'm only looking to get a fun reliable mid- (or lower) 11 sec. car. I'm restoring a 65 Falcon also. That one is getting a twin turbo 514. So I'd rather stick more funds in that one. Which is why I'm wondering where I can save some money. I had a feeling those heads would need to be upgraded. 80% street car, 20% drag racing.