This is one of Flagstaff's best problems and requires a maximum of body tension. For the v8, start on the slick as snot right hand side pull and either a pinch or mono for the left. Pop up with the left to the glued side pull and continue making hard moves to the slopey top out. You have to want this one bad to send it.
For the easier start (maybe v6?), start from a cheat stone with the right hand on the slick side pull and the left in the glued high opposing side pull. Make the same moves to the top.
Protection
Bring a pad because one can pop off with explosive force from a number of moves
fyi: the FA was done by richard smith in 1967 from the higher start, as he was like 6'5" and the ground has eroded away substantially. note that the left handhold which has some glue behind it now used to be much better.
although i have not been able to confirm whether or not the sds actually been done, it is purportedly well into the double digits. start on the obvious underclings and move up to the slick-as-snot layaway.
Actually, this is miscataloged - Smith Overhang is a problem, not a separate rock. Smith Overhang is found on the Pratt's Overhang block. BTW - P.B. & B.H. refer to this as Smith's Overhang while P.A. calls it Smith Overhang. I have always heard it referred to as Smith Overhang. It used to be that you always saw a cheater block under this problem for the start. The 2000 B.H B.O.B.B called this V5, surely describing the then standard cheater stone start. It seems that in the last few years that the harder off the ground variant has become widely accepted as the 'true" Smith Overhang. It's V8 and maybe V9 when starting from the ground, i.e. start low before the glued side pull.
I did Smith Overhang this morning before work and started to put together a sequence that might work for the sit-start. If you start from the jug low and go right to the "big" sidepull, out left there is a terrible crimp for the left hand that might allow a right hand on the bad sidepull. Finish from there as for Smith Overhang. I would estimate V12 to V13.
If you're really tall, you might be able to get the glued sidepull undercling but letting go could be tough. Probably easier than holding the crimp though.