421sbc build or 434sbc biuld

I would like opinions and expertise concerning my next build.
I am looking at building a 421ci sbc (3.85” stroker crank) or preferably a 434ci sbc (4” stroker crank). I have a stock 400 two bolt main block that is the 509 casting. It will be approximately 11:1 compression ratio with -5cc flat top forged piston, 6” forged H beam rods and AFR 210 competition 75cc heads.
The connecting rods I will be using are the Eagle 6” “ESP” 3-D-H beam that are clearance for 4” stroke cranks.

My questions are:
Will I be able to clearance the stock block for the 3.85” or 4” stroke and 6” rods?

How big of a cam will I be able to run?

Will the stock block hold up?

406chevelle


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Hi,
If I were going to build something like that I wouldn't take
a chance with a stock 400 block, I'd be looking after market
their not all that expensive for something a lot more reliable
& the cam moved up so you can run a larger cam, etc, etc.
Rich