A premium quality (304 Alloy stainless steel with rolled threads) bolt such as the bolts that we use is by far superior in quality and service performance than a weaker alloy (18-8 Alloy stainless) with cut threads. The 304 Stainless with rolled threads are up to 27% stronger than 18-8 (110,000 psi tensile to 80,000 psi for 18-8) and the rolled threads provide a much more consistent, harder and more uniform thread. Thread compound is not necessary to prevent galling of the threads either on the rolled threaded bolt or in the threaded part.

The bolts that you are asking about are called "Shouldered Bolts" These bolts are available through ARP and as far as I know, they are one of the few if not the only source for them. Before you end up paying about $235.00 for a set of these bolts, what is your purpose for the engine?  If you are trying to get 500+ hp from the engine, you may want to think about these bolts or studs. But, the 351 W uses a 1/2" head bolt whereas, the 302 uses a 7/16" bolt. If you think about it, that means that there will be an extra 1/32" around the diameter of the bolt shaft. I have two suggestions for you. One is, if this is going to be a strong street engine, you can probably use the 7/16" bolt without a problem. I can attest to this fact. I build roughly 50 engines per year for the local hobby stock circle track guys as well as many of our local Bracket drag racing guys. Several have been using the 302/351 head combination. We have successfully used the 7/16 bolt without related head gasket failures. By that I mean that when disassembled for the semi-annual refreshen, there has not been any evidence of blown head gasket or bolt stretch.

A second possibility is to go to your local hobby shop and secure some 1/2" od seamless brass tubing. You'll need enough to line each bolt hole in the heads so you may have to order it. You can also order from your local FASTENAL Co. a 7/16" ream. You will not need a ream that is carbide or titanium coated because you will just be reaming brass. Coat the outside of the brass tubing with RED loctite and tap the tubing into the bolt holes until it lightly bottoms. Then ream the inside of the tubing to 7/16. The ream may cost as much as $25.00 (that’s what I paid) the tubing will run as much as $30.00, but most hobby shops will let you order a box of the tubing which will only be about $18.00. If you choose to use this method, you'll have $50.00 invested plus a set of head bolts, but thats far cheaper than $200+ for the head bolts. AND, you can help out your friends that want to do the same combination.