PISTON CHOICE

Can anyone recommend  a specific Forged Piston for use in a 69 390 motor to end up with 10:75 - 11:1 with stock 50 cc 291C heads?

When you say specific, I assume you mean an off the shelf piston.  The ones I almost always recommend are the Wiseco for a 401 used in conjunction with a late 390/401 rod.  Unfortunately they come in two compression versions, 27cc dished would put you around 9.5 to one and flat tops with 8 cc reliefs would put you at 11.6 to one.  What you need is a piston with about 15cc dished to get a compression ratio of 10.75 to one.  That will require a custom piston with 15cc dish.  I got mine from BRE years ago, but Diamond or Wiseco or Ross are popular options.  RaceTec is reportedly the best price point for custom pistons, but even then you are going to be looking at at least $800 where Wiseco shelf pistons are $500 with rings.

These will get you closer but your going to have to bush your rods:

Wiseco does NOT make pistons for the 390 short rod short deck 1969 combination.  What can work, if you can accept 9.5 or 11.5 to one compression is their 401 pistons.  The compression height is different for a 401 than a 390.  You can buy back some of the difference by using the long rod from a 401 and this is workable.  Honestly, your best bet is probable Wiseco flat tops, Molnar or K1 rods for a 401 and later model heads with 58-60 cc to get the compression ratio down.  The pistons Trader suggested have the wrong compression height and valve reliefs in the wrong place at the wrong angle as well as the wrong pin size.

You are entitled to your opinion, Lyle.  But the piston in the link you posted has a piston height, from centerline of the pin to the top of the piston of 1.140 inches.  Replacing a 390 piston with a 1.553 "ish" height will put the piston about 0.460 inches down in the bore at TDC.  Chevy parts can be made to work, but not the ones in your link.