The GHIA was EFI as well ... just SOHC.
Still had plenty of go though ... Mum bought her KF manual GHIA new in 1990 ... and sold it eventually in 2005 I think it was ... that car still went strong ... and looked the goods as well.
I learnt to drive in that car ... still had standard engine/gearbox/clutch in it ... had the Whiteline works kit in it though as the old suspension was tired and needed replacing.
In the end ... the cost of a conversion may be just as much as selling your currently GL and getting a GHIA or TX3 non-turbo ... and more specs in the higher models and better interior as well.
The old girl not long before it was sold
Damn it was a fun car to drive ... solidly built.