My plan is a little different than yours but if this helps I'll share.
I'm building a 65 AWB Coronet...reaching it to work on will be a huge PITA.
I used the factory end of the original frame and attached it to a set of leaf spring slider brackets attached to the new frame added for the chassis.
That allows the factory radiator support, fenders, bumper, grill and hood to be slid forward in one piece.
I'm doing mine as a flip nose but could easily be removed by taking out the two front bolts in the sliders.
Mine is still primitive and I haven't worked out all the bugs yet.
Here's a pic of what I have come up with so far...