NM.
I am speaking based on what my engine builder has indicated so do go into that me building your engine crapola.
Ok, let's make this constructive. What facts do you have since you are disputing the strength of the 351 block?
tick..tock...Silence is deafening...tick ..tock..ok, looks like maybe you should have had me build your engine, hehe..
Here are some
F-A-C-T-S (facts are good) listed by 5.0 Mustang magazine:
"If you’re considering extra cubes, then chances are you’re wrestling with a fairly common dilemma: Do you build a 347 out of your 5.0 or step all the way up to a 351? Perhaps the following info will help you decide.
351W: Advantages
• Strength: The 351W block is stronger than the production 5.0 by a long shot. Thicker walls and 3-inch main, and 2.311-inch rod journals (versus 2.248/2.123 for the 5.0) are contributing factors.
• Taller Deck: The 351W features a deck height of 9.503 inches versus the 5.0’s 8.206 inches. This means a longer rod can be used for even more cubes—up to 435 with a production two-bolt block, and 454 cubes with a four-bolt FRPP block, according to George Klass at Coast High Performance."
...more F_A_C_TS..
"Stroking the 351W
The quest for additional power is insatiable for many Mustang enthusiasts. If a 150 hp shot of nitrous is good, then 200 hp is even better. If 10 psi of boost feels good, then 14 psi should feel even better. If a 302 makes 1.5 hp per cubic inch, imagine what it'll do with a 351W, but why stop at 351, why not 383, or even 427 cubic inches.
351W conversions are becoming increasingly popular with many of our customers. With the widespread stroker kits available for 302's, attention is now being focused on stroking the formidable 351W.
There are several benefits to stroking a 351W over a 302, the most important is block strength. The factory 302 block is inherently weak and doesn't hold up well to serious levels of power and torque. The 351W on the other hand features a much beefier block design and is more suited to high levels of power and more demanding environments." - Alternative Auto Performance
Mt. Clemens, Michigan 48043
"The advantages of using a 351W vs a 5.0 (302):
FIRST, you get an extra 49 cubic inches of displacement. As the saying goes, there is no replacement for displacement. Second, the webbing in the lower half of the block is thicker, making the block stronger. Third, the crank has bigger main and rods journals, making the cranks more durable than their 302 counterparts."
EDITED for smilie content!