Remeber; Ford's redline considers that they can get the motors for free!
The 514's are 2 bolt main blocks, and I don't think i'd push them past 6000. The lower half of the 460 has always been suspect because the main caps tend to 'crawl' at extended rpm...which is why the made 4 bolt main 429's back in the day. If you're going to use a 2 bolt main, i'd strongly recc'd a stud girdle. Even then, I would not push much past 6500 or so for any length of time. To be honest, with a big 385 series motor in a Cobra, there aint many times you're gonna NEED more than 5000 to make you're point! Only other consideration:
OIL CAPACITY! Definitely run an extended
oil pan, preferrably rear sump and run a high volume
oil pump (I like Mellings). The more oil you can get in the system, the safer youre gonna be. I run a big pan, twin remote oil filters and an oil cooler...and i'm still scared shi*less that i'm gonna starve when I push the rpm limit.