Good luck with your research but frankly, there isnt much you will be able to find about them.
I was very fortunate to find two of these snakes in June this year, I was searching for them for about three years. I got two male Spilotes sulphureus (not sulphurus), so now I am searching for a matching female. These snakes are probably even rarer here in Europe than in the US, I contacted every dealer in Germany, France and the UK who is still importing snakes, but no luck so far.
Jason Hood got some young snakes from one of his pairs, but I dont know if he is willing to sell any of them (if there are any left at all).
The two males I got are semi-adult, they are about 180 cm long (ca. 6 ft). From all accounts I was able to find this snake might grow to 300 cm (10 ft) or even longer. My snakes are WC, but the previous owner had them for some time.
I already wrote some information about them here--> New Additions
and here --> Update Spilotes sulphureus
And some new pictures
Both male Spilotes sulphureus
Spilotes sulphureus Male #2 looking for his meal