If the bores are in nice shape, I would leave them alone. 0.040" overbore is max for most blocks. Leave some room for another rebuild. That small displacement increase won't buy much.
I think some people are suggesting you stroke it out to a 408. You already have good rods, and you are buying pistons to increase compression. A crank could be purchased and all parts balanced for maybe an extra $500 or so. But you should look at the price of a complete rotating assembly and compare both ways. You should be able to sell your existing parts and recoup some of the money.
Just be careful of letting all of us spend your entire budget on the engine. For another $2500 bucks you could buy an aftermarket block with a 4.125 bore. It is stronger and has much better oiling. You could have 427 cid or more.
