Re: '61 Vette: When the cloth top is locked down to the windshield there is an opening of about 3/8" between the center of the windshield and the front top bow.

Secondly, when the rear hold-downs are locked in place there is a 2" opening between the back bow and the deck.

Can anyone help me with the adjustments?

 

Welcome to the forum. Sorry I missed this but the only thing I can offer is to check the factory service manual or the assembly manual which is available from the Corvette aftermarket suppliers.