Welcome to the forum, and what a great motor to get back into FEs with! Given the end use, I'd be much more worried about the block than the LeMans rods. I don't think the rods will give you a bit of trouble if they Magnaflux OK and have the good bolts. Usually when you sleeve two adjacent cylinders on an FE, you can develop cracks at the deck in the thin spot between the two cylinders. Is that where the Lock n Stitch pins are? Maybe that's a solution, but I don't know for sure. If you put it together with that block, just be aware that you are running a risk, and if you start seeing coolant in the oil, or white exhaust smoke, you'll know where its coming from.
What intake manifold do you have for the engine? Just curious.
One other thought would be that big cubic inches would help keep the flow velocity up in those big ports, making the engine much more street friendly. So maybe think about a stroker kit; that would require different rods, and take the concerns you have with the LeMans rods out of the equation.
Here's a couple of threads on tunnel port builds here, to give you some ideas:
http://fepower.net/simplemachinesforum/index.php?topic=729http://fepower.net/simplemachinesforum/index.php?topic=2489