some slant six info at this site
A durability legend with performance upgrades: Mopar slant six engines
I have built a few slants, for me they are fun to work with, mine have good performance and driving capabilities. One item of note: with V8's folks can generally buy performance engine parts from a catalogue or big box performance store, with slants, typically one needs to adapt parts such as pistons, valves from other applications and specify cam shaft grinds as there is not much if any performance slant six parts available across the counter. To me that makes it more interesting.
