Hi Mate.
The Y block is a great little engine, yet after market parts are far and few between.
Are you planning on performance or style?
If your careful they bore and stroke above 300cu
Pistons for a 292 are cheaper than 272. My block is a 272 bored out to 292 and .030 up.
Do you know what heads are on it? I guess you could say the Y Block was the stepping stone from the Flat head to the Windsor.
And there not the best breather but if you are working towards triples then revs. won't be a problem as tests show they are the better of low down power.
There are several casting no. and locations which will guide you. A good place to start with identifying your Y Block is
John Mummerts web site. He is also a member of this site.
His site at the bottom of the home page offers Technical information, Casting id. etc
Oh you have to click on the pictures to open the next page.
Ted Eaton is another knowledgeable guy which you'll find has done a lot of testing and posted it for us to lean upon when building a Y block.
These two guys are the ones you might find a book written buy.
All the best.