Perhaps you have already seen "Pulaski et al. 1988. Biotechniques 6(5)p.470" ?
I think the article focuses on optimizing ligation efficiency in such
contructions however it might be worth giving the authors a call at
UpJohn. Nicole Theriualt at Kalamazoo, MI is the corresponding author.
J. E. Graham
Biology and Chemistry Departments
Indiana University Bloomington