Well Greg, I don�t know YOUR 0805 Pads but if you look at the recommended pattern for 0805 in IPC-SM-782 you might notice that the Z-dimension is somewhat about the size of your 1206 part length. With that and assuming that you ask if the results will still comply with IPC-A-610 I would say NO CHANCE.
If you happen to have larger pads so that your joint will meet your or your customer expectations you should look after your paste deposit to prevent excessive solder beading, just print/dispense for 1206.
Electrical characteristrics (unless it�s somekind of weird RF-stuff) and solderability should not be the problem. Solder joint strength for these parts is greatly determined by the toe fillet and not like it is with gullwings by the heel fillet. So look that you get enough toe fillet.