The first Vespas allowing for such modifications are the VBA/VBB models. The VBA (the designation comes from the prefix-frame numbers) was introduced in 1959 and equipped with a predecessor of the modern PX engine albeit only being a three-speed. The VBB followed in 1960 and was a four-speed. All modern large frame motors and small frame forks (which have a similar length to the original items) including their suspension units fit plug & play.
The stunning VBB model you see before you was customised by German Scooterist Clemens Biber (supposedly no relation to Justin). What you see here is the result of a smart concept: enhance the genuine styling of the original machine and employ modern technology to make it a safe, reliable and quick every day transport.
While the VBB is not considered part of the wide body family it is still one of the curviest Vespas built. So Clemens tidied the whole bodywork up and had it sprayed in a vintage silver. The fiberglass base of the modern sports seat was modified and now slopes down a lot farther, nicely complementing the classic lines. The tank on the tunnel comes from an old light truck and has been altered for storage so it replaces the toolbox.
The forks were transplanted from a Vespa PK and fitted with a semi-hydraulic disc brake by Grimeca and a modern aftermarket shock. The engine was salvaged from a Vespa PX. The positive side effect of both modifications is that Clemens can now use the safer ten inch wheels. Apart from the larger diameter he also benefits from a bigger choice of tyres compared to the original eight inchers that have hopefully been destined for duty on a wheelbarrow and never see tarmac again.