Yes it's a 351. The 400 has a vertical ridge just to the right of the distributor.
Typical but not 100%. Some of the 351M blocks (same block) don't have the fin.
With those 2V heads - if they are salvageable - you won't need port tongues, just so you know. If the block has to go over .030 to clean up, it's iffy because all those, like the other SBF units, are thin wall cast. 2V open heads, decent cam and attention to detail can yield 400 HP or better easy. Casting numbers for the heads are under the intake ports, casting number for the block will be right side (starter side) near the pan rail. Unlike an FE, you can get a reasonable picture of the application from the casting #s for a 351C. Your heads have the "2" cast in, which means they are likely early - pre 73 - heads but the casting number will confirm that. Anything 2V post 73 is iffy because of emissions changes and heat in the exhaust. 1975 up Ford put a cooling passage around the exhaust valve guide which makes the exhaust port almost unusable for anything but show and shine. Post 71 2V heads are very prone to cracking in the exhaust seat area, so 100% they should be magged before any work is performed.
