you can't make G from 1,4... the reaction will not happen..
You can drink GBL diluted in a drink, little or no difference from straight GHB. 98% GBL has alot of impurities. You make G with 98% pure GBL you'll get sick real quick.
1,4 has been known to cause kidney damage. I would stay away from the stuff.. If you can get a source for GBL.. just get that and your good to go.