should I tune it up even though it runs fine

Use a high quality oil and filter. I like Kendall GT-1 or a Castrol synthetic blend. Keep it properly tuned up, don't wait until it starts to run like poop.

$500 for a V8 rebuild kit is good. $1000 for the labor is also pretty good. Length of time depends on how much is done.

IF YOU WILL GET A CHILTON'S OR HAYNES MANUAL, NOT ONLY DOES IT SHOW REPAIRS AND OTHER STUFF..........

THERE IS A SECTION ON SCHEDULED MAINTENANCE----ABIDE BY IT!!!

WILL TELL YOU WHEN AND HOW TO PERFORM THE NEEDED MAINTENANCE

PERSONALLY W/ MY JEEPS, I DO SOME OF THE STUFF SOONER THAN RECOMMENDED

I ALSO CHANGE THE OIL AT CORRECT INTERVALS, IN MY 1977 CJ5 258 6 CYL, EVERY 3000 MILES----IN MY 1946 WILLYS L-134, EVERY 2000 MILES I ALSO SUBSTITUTE A QUART OF LUCAS OIL STABILIZER

I REBUILT BOTH ENGINES IN 1996, I WAITED UNTIL MY FOURTH OIL CHANGE (TO BREAK IN THE RINGS TO THE CYLINDERS) BEFORE I STARTED USING THE LUCAS (REG STUFF, NOT THE EXPENSIVE SYNTHETIC)

I DRIVE THE CJ5 (MR. JEEP)DAILY--AND THE ENGINE HAS OVER 200,000 ON IT NOW (NORMALLY THE 258 WOULD LAST ABOUT 100K,BEFORE IT WOULD NEED MAJOR ATTENTION), VACUUM IS A STEADY 21hg.......I'D DRIVE IT TO THE OTHER COAST RIGHT NOW! (YOU SUPPLY THE FUEL BOTH WAYS!)

"WILLY" IS DRIVEN A GOOD BIT, BUT NOT GOT THE MILES "MR. JEEP" DOES-----SAME GOES FOR A TRANSCONTINENTAL TRIP IN HIM!

WHEN I BUILT BOTH, I SUPERVISED THE MACHINE WORK (I HAVE SOME EXPERIENCE) KEEPING TOLERANCES TIGHT, AND PERFORMED "SMALL TRICKS" WHEN ASSEMBLING....LIKE CHAMPHERING OIL HOLES, ETC, USUALLY TAKEN FOR GRANTED AND LEFT ALONE

GOOD LUCK

THE MEDIC