Here is a potential starting point for the body-buck; a "wide body" Devin.
I do like the look of the headrest fairings on the Hagerman (and on the 300 Mercedes, etc.) so that too is part of the plan.
As for use of modern interior components, that would not be something that I would consider... it's just not what my "esthetic" would be. (As an example, I am struggling with the thought of putting a Kirkey vintage race seat in my FIA; the GT350R model driver's seat presently in the car is correct, but
very uncomfortable after an hour or two.)
Presently, I have my 66XKE seats in the ERA JagV12 chassis to set up the steering wheel location, dash clearance, cowl height, etc. I have a line on some 68 XKE seats, which are about as "modern" as I plan to get.
Jim