I would think the curvature of the Dish would have to match so that signals are the same as the smaller dish, but also, bolt patterns for the backing structure, the length of the feed arm might all come into play
The Virgin Island dish is designed for 2 satellite positions. 119 is received from part of the surface area and reflected back to the LNB at the correct focal distance. 110 is received from a different part of the 30" circle on a LNB at the correct focal distance for that satellite. Look at the spacing of the LNBs.
Dish 1000+ has 3 focal points for 110/119 & 129 for Ku band and a 4th focal point for a different frequency international satellite at 118.7.