Vince, Hers's a link to Keith Blacks' web site (Silvolite pistons) and their 307 piston they list their compression hieght as 1.665. This compression height is what they advertise for their piston, it may vary with other manufactures.
http://kb-silvolite.com/spistons.php?action=details&S_id=240 If you go to the web site "Diametrical" listing you can go down to the std bore 3.875 and look thru what they have for compression hieght in that bore. You will also have to watch the pin diameter. The pin diameter can be worked with if you want to change from a pressed pin to a floating pin and there has been a recent thread on that. Also note what Twisted6 has taken off the top of his pistons. Hope this helps solve your dilemma.
Larry
