And now for something completely different..and an appeal for assistance.

After many months of blundering around in the Hellenistic world I've decided to try something different, namely the South American wars of independence circa 1820. I've started to root out information on the internet and in the somewhat limited sources available in English.
An honourable mention should be made here for "Regimientos de Americas" a small Madrid based publisher who have started to produce a series of booklets on the conflicts in South America in the early 19th century. They also sell a remarkable series of replica patches issued by the various revolutionary movements to commemorate their divers victories. The one below was issued to British troops serving under Bolivar.

Now while this is all well and good it doesn't help me with a fundamental part of driving the project forward, namely suitable figures in 25/28mm to bring this series of conflicts to the tabletop.
The Spanish forces shouldn't be a problem given the ranges of Napoleonic figures available. Likewise the Riflemen of the British Legion serving under Simon Bolivar shouldn't be too difficult to source either.
Where I do start having problems is with the other units in the Armies of Bolivar & San Martin:
British Legion infantry, similar to Napoleonic British but with plain jacket & bell shako. Would late Napoleonic Prussian figures be more suitable?
British & Venezuelan hussars, again fairly typical hussars but with bell shako. Which nationality would offer the closest match?
Argentinian infantry, from what I can make out French Napoleonics offer a fairly good match ( even the forage caps are quite similar) but would Spanish or Portuguese be closer?
Ideally I'd like to use plastic figures for ease of conversion & economy.
I open the floor to you Gentlemen and look forward to any suggestions from those of you more knowledgeable than I on this period of history.