The car is a ’55 Crown with a 272ci, an E-4 cam; otherwise stock.  3sp O/D, 6v.  I currently have the stock 2bbl and Load-O-Matic.  My ultimate plan is to install my Edelbrock 553 based tri-power that I’ve had for 45+ years, knowing that the LOM has to be replaced.  And knowing a modern 4bbl or EFI would be an easier install and outperform the vintage tri-power.  The goal of the car is to have a reliable cruiser that sounds good.  Not looking for ultimate speed or HP.
I’m wondering what advantages, aside from the very obvious, there are to rebuilding a ‘57+ unit vs using a remanufactured dizzy that utilizes a more modern core.  Do the newer cores offer a revised design that is seen as superior?  Availability of parts?
Some time ago, I purchased an Autolite remanufactured unit that was advertised as using an original case – they just didn’t specify from what.  The unit I got is a D8TF which I believe is from a 1978 truck.  The good news is that the dimension from the bottom of the gear to the end of the shaft is .995” and shaft diameter is slightly undersize at .4625”.   Before I proceed much further, I’d check all the dimensions against the original and do the “see if it even fits” test. The issue is that there is no extended collar at the top to ride on the block when installed.  Instead, there is a stepped down, beveled shoulder.  The bottom edge measures 4.997” – slightly more than the target 4.991-4.996” – from the bottom of the gear.  I’m thinking I could have my local machine shop turn the shoulder square, permanently install a split collar and then machine the bottom surface to 4.991-6”.  The OD may need to be turned down to fit the recess in the block.  I’d then reinstall the guts including different springs and bushings to change the curve while also changing out the points and condenser.
Or should I find a rebuildable ‘57+ unit?
What are your thoughts, experience or advice?
Thanks
Mike