I have made two blocks. One 4" thick and one 7" thick. I also have bought ones to compare with.
I strongly recommend maple and a beech or maple edge board surround. If you are making a proper block, which is usually two feet deep or sometimes 30" and whatever length suits you (2, 4 or 6 feet usually) then you will definitely need a means of putting threaded rods through. Don't think that you can avoid this and rely on glue alone as you will regret it. DAMHIK. There are various different methods used for pulling it all seriously tight, including metal bars rebated in which the rods pull against, these bars being hidden by the side and end boards.
I buy most of my hardwood here (5 mins drive from me and their stock is good quality - they also sell online)
https://www.exotichardwoods.co.uk
They give discount for trade and volume purchases.
Your biggest issue is
exact sizing of the blocks used and the method you intend to use for staggering the joints. Your life will be made much easier if you do all blocks the
exact same thickness in one dimension and variable in the other so that you can plan a joint stagger. Most commercial blocks these days use finger joint profiles on the 'same width' dimension and a flat face on the random one. This at least doubles the glue area and means that most of your rod pull only needs to be in one plane (usually the long side of the block).
You want to be certain that all of your wood is well seasoned and dried to exactly the same moisture content. It is a lot of work so don't skimp on top quality wood. You need a fairly long open time on your glue - I used cascamite but that was before the changed the formulation a couple of years ago. And plan ahead and make a softwood clamping frame so that you can exert plenty of pressure evenly spread, with plenty of heavy duty sash cramps.