I have no problem using A or A+ blocks for builds. I'm currently way down on blocks. I do have several blocks with cyl wall damage. I'm consedering the cost of having them sleeved back to std and starting over with them. I have also been using AH Sprite / Midget 1275 inline blocks with the rear cap trimmed to fit. A+ power unit cores are getting ever more difficult to find at a reasonable price. Well they are hard to find at any price. I now have one A+ 998, three A+ 1275s at the machine shop and I'm pricing my last A+ MG Metro core power unit for a street build. I should have a 1275 GT block (that's A ) and maybe a 1275 A+ block left to work with. Next issue will be finding good cranks. Steve (CTR) 

You can fit the A+ backplate, timing cover and tensioner to any A series block. I did it to a Cooper S recently because it had been align bored and the timing chain was too loose.
Likewise you can mill 5/16" of the lump off the A series conrod caps without detriment.

I know of some who specifically stay away from A+ blocks.  There is also a run of 1275 A+ blocks that are linered from the factory because of porosity problems.

I've also known some people who have spent more $ than they should have just so they could have an A+block.

The best things about an A+ (In my opinion) are the timing chain tensioner setup from the factory and and the rolled radius crank and the 1275 rods don't have the heavy balancing pad on them.

Good info...Thanks

I presume the A plus is the more desired block?

It depends who you talk to. The A+ has strenghtening ribs in it but some say it is cast from softer metal. It also has the distributor mount the same as a regular car and the alternator holes are closer so you don't need the large afterthought Dynamo to Alternator bracket. The A+ block has the timing chain with a built in adjuster/tensioner so no more timing chain rattle, it also has the much lighter Verto clutch.

What is the difference between an A plus block and non A plus block? Is one more desireable than the other?