Pics of the car today would as stated be helpful.
Here is what Draglist says:
SRD Racecars for all the Vega's they have listed for Ronnie Manchester.
Also shows them all as 331c.i. and 4 speeds.
Link to a bunch of Grumpy XI chassis pics from SRD below. Built to Grumpy specs they might have some similarity to your car that helps identify it. From the pictures something as simple as hood pin location or mounting holes for cowl gauges can be a start:
https://www.google.com/imgres?imgurl...&iact=c&ictx=1