Using a MX5 rear end on a registered kit, IVA ?

[waynesworld]

Hi all, i am thinking on upgrading the rear end on my kit car, at the minute its is registered, but it is running a MK1 Escort rear axle on 5 link setup.
Now the idea is to swap that for a complete MX5 rear subframe, so subframe,diff, shafts hubs all but the Shocks, i will use the coil over i have so just new tabs for mounting them.

Question is, if i do this will it be back to an IVE test due to the work done?

wolly