Yep Nathan is on to it
Nup
In a disturbing rare twist for the Forum it appears that Nathan may be wrong
There is no realistic/legal way to get a bike built on an 83 KDX200 frame through rego.
There were plenty of legit registered MX bikes back in the day and one of the criteria for putting one on classic Reg is previous proof of registration history.
From the Vicroads website;Existing and ongoing requirements to be noted
There are two important existing, ongoing requirements that permit applicants and club safety officers/scrutineers need to be aware of:
Motor vehicles manufactured outside of Australia after 31 December 1968 (30 June 1975 in the case of motorcycles)
which do not have a previous Australian registration history, must have a VASS approval certificate to demonstrate that the vehicle meets the Australian Design Rules that applied at the time the vehicle was manufactured.
Club permit vehicles must comply with the Vehicle Standards, appropriate to the date the vehicle was manufactured, contained in Schedule 2 of the Road Safety (Vehicles) Regulations 2009.
And from a Vicroads PDF;4.3 Previous modifications
An existing CPS vehicle that has, at some time in the
past, undergone a modification that is an assessable
modification according to these guidelines, does not
have to be re-certified to retain its permit provided:
?? Evidence of Australian registration history in its
current modified condition can be supplied; or
?? Evidence in the form of a VASS Approval Certificate
Plenty of info here
https://www.vicroads.vic.gov.au/registration/limited-use-permits/club-permit-scheme/changes-to-the-club-permit-scheme-from-31-january-2015From what I can make out the the frame is considered the main part for rego and the motor can be swapped for a similar engine with a different engine number.
Also this is for Victoria so may be different in other states.