Hey man, no offence but seriously '90 GQ's in good condition and lowish k's go for 10k absolute maximum, nowhere near 13k.
And your engine is a converted turbo, not even original, let me throw some figures at you.
Buy a low kay good condition GQ for 10k, then buy an original RB30ET out of a VLT that has been fully decked out with all the good stuff, bigger turbo, cooler etc. for about $3500 that would have 200-250 RWKW and spend $1500 on the conversion and you have spent 15k on a car with 100RWKW more than yours and is an original turbo. And even then conversions aren't worth squat, sometimes they are worth less than the original.
You are at least 10k over the mark, considering you could build your own immaculate GQ RB30ET with 200+RWKW's for 15k or less.
Not trying to kill your sale, but at the price you are asking there will be no sale anyway.