I couldn't find a current vendor, either. Dave's right, Baker Creek has been very chatty in the past, and they sure know old seeds!
I did find a detailed description:
NC State University has a Cucurbit Breeding department or sub-department, and they publish a "Vegetable Cultivar Descriptions for North America" with a section "Watermelon (M-Z)
"Schochler - Vendor: Robert Buist Co. Characteristics: 90 days to harvest; a very large melon used extensively in the South, having outstanding shipping requisites for size, tough rind and quality; fruit very long, 40 to 50 lb., rich dark green with faint stripe; flesh bright crimson, fine grained and very sugary."
I Googled "Robert Buist company" and found a lot of history about him, but as far as I can tell, the company is no longer in business.
The seed, nursery and greenhouse business was in Philadelphia.
67th Street was the last address I found.
He died in 1880 of pneumonia.
He turned his seed business over to his son Robert.