True, that is a 3.75" arm with short compression height pistons which can lead to the pistons rocking in the bore and increased wear, I get the impression that he wants the motor to last too. There are still a LOT of 383s out there.
If he wants to go with a 318-390, sure go for it, maybe @MrJLR can chime in on his 390.
There as many options as his imagination and wallet will allow. First thing is research. It is time to nerd out and buy a bunch of books to learn what is available. After all my nerding out, consultations with my bank account, reading tea leaves and chicken entrails while inhaling the incense of roasting tires, the Thunder God of Torque commanded me to build a stock stroke LA360 first, then to build a 400-470 B block.