What does the guidance actually say? There are two separate sets of rules - one for 'rebuilt' and another for 'radically altered' vehicles. 'Radically altered' is defined as "vehicles which are substantially altered from their original specification, but which are not kit conversions" (think Vtec with metro front subframes etc). The two sets of rules are similar although not identical.
For rebuilt vehicles, the rules state that in order to retain the original registration mark (direct quotes from VOSA website are in italics):
Cars and car-derived vans must use:
The original unmodified chassis or unaltered bodyshell (i.e. body and chassis as one unit - monocoque); or a new chassis or monocoque bodyshell of the same specification as the original supported by evidence from the dealer or manufacturer (e.g. receipt).
And two other major components from the original vehicle - ie suspension (front & back); steering assembly; axles (both); transmission or engine.
If a second-hand chassis or monocoque bodyshell is used a car must pass an Individual Vehicle Approval (IVA) and light goods vans must have a enhanced single vehicle approval (ESVA) or single vehicle approval (SVA) test after which a "Q" prefix registration number will be allocated.
For radically altered vehicles a points system is used. Vehicle must score eight or more points to retain the original identity and avoid the need for an SVA test. The following values are allocated to the major components used:
chassis or body shell (body and chassis as one unit - monocoque ie direct replacement from the manufacturer) (original or new) = 5 points
suspension = 2 points
axles = 2 points
transmission = 2 points
steering assembly = 2 points
engine = 1 point
so with the OP using all his own suspension, axles, engine/gearbox and steering from the Original (VOSA do allow like for like new stuff too, so it can be replaced during the build) he should just squeak through with 9 points
HTH
Martyn
Edited by Honda-Mini, 28 May 2020 - 09:02 PM.