Yes, I can build you one. I keep the proper Z-section on hand and build chassis to suit +4's, 4/4's, and +8's. I will match anyone's price.
If the frame is rusty, the wood sills/rockers will likely need to be replaced too. Probably the firewall will need repair at the bottom, and the inner edges of the front wings will need attention.....
I actually have just about anything you need. I assume this is a 4-speed Moss box car. Very, very cool and desireable.
We may actually know the previous owner if this is a recent purchase? Did it come from Dennis Glavis at Morgans West?
You can contact Morgan Motor company, but supposedly Morgan spares (morgan-spares.com) has been granted sole rights for US parts distribution. I have recently heard of some instances of people being able to go factory direct, though.
There is another source in British Columbia if that is closer to you. The name escapes me, but I can find it if you like.
I'm happy to help with anything you need, whether you choose to do business mith me or not. It's all about keeping the cars on the road, and the Brotherhood of the Mog.....
Eric