Ahh,the good old HQ,no doubt the best colour for that model too.If it was me i would restore it to original again,keep the bench seat and interior colour too.Id bolster up the seat to give some support as they have none.
Build the running gear nice and strong and ADD all the features you want.
Dont lighten it up to get more power just give it enough power so you never notice the extra weight.
I got a HQ kikgswood a few years ago for $700,dark green 4.2 tbar auto,factory black bucket seat interior(mint)The old guy had every reciept from day one(including fuel)and the thing never had a radio fitted just the black panel.
That one should have been a keeper(need to checkout the HQ Statesman i found hidden away nearby)
Good luck with it.