Luckily, although shipbuilding was more art than science in the 16th through 18th centuries, I am finding that the Spaniards did provide a tremendous written record. For example, the Spanish government issued a series of detailed instructions specifying exactly what they meant by the term "Galleon". According to Kirsch, and to Konstam, we know the proportions, their armaments, their provisions and how they were fitted out. We also know how they were built. There is also a wealth of pictorial evidence of what these ships looked like and there is a large amount of archeological evidence to support the documentary evidence. But, there are no available plans of specific ships, only artwork.
The more I read, the more I am finding that the Revell kits are not so comical. The common hull used in both kits closely match the 4:1 length to beam ratio stipulated by the Spanish government. There is pictorial evidence showing similar hulls, as well as models built throughout the period in question. The sails seem wrong; Professor Tilley said earlier in this thread that the typical ratio for spars was that each spar was roughly 1/2 the length of the one below it; that seems an appropriate observation based on the period models of Galleons in Spanish museums and the pictorial evidence found in period artwork. Additionally, the armament seems correct in these models for the period in question, as do the fittings.
In short, both kits can be said to be the basis for a suitable generic model of a Spanish Galleon of 1588. However, the model named "English Man o' War" does not match English ships of the period, either in proportion or in detail. One point of interest in the "English" kit is the bonaventure mizzen mast. Another point of interest are the double stern galleries found on both kits; there are many paintings showing this basic hull configuration with two, one, and no stern galleries. This could be an interesting way to build both kits into respectable models; build one with either one or two galleries and the other with none.
In other words, I think that it can be done! It may take a lot of work, but I believe that these kits can be made into respectable ship models of generic Spanish Galleons. I thank everyone who steered me towards the several references that I am now using. This was quite a find; both kits for $1.00. Incredible!
Bill Morrison