Hi,
As you have found, the process can be a little bit of a minefield & at times also like a lottery, i,ve heard that some builders have been issued with a "New" current registration even tho they may not have fulfilled ALL the requirements to attain a "New" registration.
With regards getting an "Age related " registration.....If you build your car from a single donor ( as I have done ) & that car is registered in your name ( which is kept on SORN during the build ), when the time comes to register your Roadster you submit the relevant forms stating you have built from a single donor ....Reg number such n such.....VIN number such n such & then you "SHOULD" ( tho open to lottery scenario subject to some DVLA offices )receive an "AGE related registration, this being of the same year of your donor vehicle but NOT the same registration number .
The chassis number of your Roadster is usually given to you during your build once you have requested it from the DVLA ( local office etc ).
On a personal note .....My donor was a "G" reg Sierra 1990 & so if all goes well for me I should receive a "G" reg plate for my Roadster ...hopefully
I Hope this helps a little,
PS, there is a download available on the announcements section of the forum for a Letter to send when requesting a chassis number from the DVLA.
I hope you enjoy the forum & best wishes for your build.
cheers
andy