I would try a call to Sureterm Direct.
www.sureterm.comIf you are to be the principle/main driver on the Insurance,
then
One additional named experienced driver,
with a low risk proffesion & their own insurance may be the cheapest,
2 named drivers might be a little more expensive.
Thats if the vehicle is registered to you as the Owner/Keeper.
(Some companies do recognise parent/guardian named drivers as of equall drivers on the insurance,
eg Swinton & Admiral Multicar for just normal/unmodified vehicles)
Limit the annual Mileage. (they can check by your MOT's & your declaration,
make sure every detail of the vehicle & modifications are declared)
They will want to know if its Social & pleasure use only,
commuting to work or education will put the price up again possibly.
Kept on private ground/drive & kept there during the day (not at a workpace),
& parked at the home postcode at night may be cheaper.
If the Vehicle is no longer on the original Registration number it may be considered as a new/rebuild not modified,
thats not a problem with Sureterm,
they may be asking for an engineers report,
but you being under 25 years old with a modification or rebuild might be the stumbling point.
www.premiumchoice.co.ukare not doing young drivers now with modified, or they were not earlier this year.
'Footman James', '2gether' & the usual 'Adrian Flux',
'Carole Nash', 'NFU mutual' etc are all worth trying.
lots of them have changed the minimum age of drivers this past year.
With the NFU & young drivers, it helps if a family member is already insured with them.
Hopefully someone here has recent experience of getting cover.
all the best
george