Beside HUGHES ( PN 1256 ), what other vendor does have that measure on retainers that could keep the stock installed heigh OR maybe add some stationary pressure without use shims ?

and on a similar price ( or cheaper if posible )

You may have to research several of the cam companies to see what they offer.
The Hughes 1256 Retainer is 3/8" stem, 7-degree lock, +0.075" install height, 1.375" outer diameter,
1.130" middle step diameter, and 0.730" inner diameter, and cost $62.00.
Are you looking for a retainer with the same diameters, but without the increased install height?
Which valve spring is this for? If it is for something like the 1106 spring the spring is a single with damper, 1.540 OD, 1.130" ID.
I think it would be easier to just shim the spring ?
Manley has a 1.130" 23636-16 standard height retainer, but it is for 10-degree locks. The retainers are $50, but you would need the 10-degree locks too (Comp 612-16 are $20.00.)
A Comp 749-16 may work $49.25 (1.125" id), but it is also for 10-degree locks.

I just found this one that may also work, Lunati 75713LUN. This is for 7-degree retainers, and is 1.500"x1.125"x0.700", and costs $44.95.

FWIW, I priced these from Summit.

Lunati does look a good option, but doesn't say about installed height

will 1.125" be a noticeable diff from 1.130" to get worried ?

ok, great!! thanks for open the options to me...

Since is not for race and really for street, I don't think .005" clearence will be something to worry, but will ask around.

Now... WHAT'S the stock installed height of the 452 heads assembly with stock on everything ? ( lock and valves )

I mean... hughes says 1.880" installed height for that spec ( and that was teh test I made ), but I don't know if thats the Original height on the pure stock assembly... I read somewhere stock height is around 1.83" to 1.86" and that will mean will add some pressure on this used springs ?

dunno if important but still some pressure add, and if so, then Lunati retainers are even more a better option ( beside the price by Summit, althought the clearence )

I'm also assuming the stock valve locks are 7º... right ?

stock locks are 7-degree. The only way to make sure the install height is correct is to measure it because valve jobs, shims, spring cups, etc will change the installed height.