The adventure begins!!!
Everything below is of course just me doing the project in my own minds eye - its your car, your work, you only have to please yourself and as its you doing the work if you get it wrong its not such a big deal to put a part in the bin and have another go. That's the hobby...
...but if it was me
I think the first step is to get it up on some tyres, and as its never going to be a "correct replica" 17in are just fine, then gets lots and lots of cardboard and experiment with bonnet vs body vs grill vs wing lines. I expect it will be a new bonnet, maybe using louvre panels from what you have if you can't get a good price for it as is. A "cut and shut" on the front wings, what are they made of? The steering column extended to sit just right for you and a remote gear change.
From memory you are TALL. I assume that goes with big feet so its worth planning ahead for space and what's a comfortable angle. Maybe a new bulkhead or an extension for peddles. Peddles are something to think about in the "planning phase" before you are cutting and drilling.
For the radiator its a question of budget... Mine has a mini core and plain tanks made up by a local specialist. From memory there's one from a Honda Civic the right size with pipes in the right places. Chris Gould recommended a particular Austin Maxi radiator? Original tanks but modern core is the compromise most make. An original style core is lovely, but its an expensive item.
I suppose THE question is are you happy to compromise to "get it going" then improve over time, or are you wanting to get it "finished" before it rolls out?
Another question is do you want to pressurise the system or is steam in the face and topping up at the top of long hills all part of the fun?