3.73 is ok but I would use a little more stall. 2500 should be a good one to use with the 3.73. A 3.73 used with a 327 will lower the stall a few hundred rpm due to less low rpm torque and a higher gear. A 2000 stall will feel weak off the line.
A 3.73 with a 700r OD will yield a 2.70 top gear. Which is 2500 rpm at 72mph with a 26 inch tire. So, a 2500 stall should be ok. You can get that in a lock up converter also.
A 270H will make more low rpm torque and a 280H will pull harder on the top end. So, both cams will work fine, just choose the cam that better suits your needs. A roller will make more torque and hp but adds to the cost a lot. You really will have a hard time feeling the difference with the flat tappet versus the roller cam.
I'm thinking you will like the 270H better than the 280H. In both cases, use 10:1 cr with aluminum heads. 9.5:1 minimum. You will find it is harder to build compression with a 327. A 350 with flat tops and a 64 cc head is the perfect combo for you. A 327 will need domes to make that compression and domes are bad on flame travel. Plus the extra 1/4 stroke of a 350 makes a big difference. If you ever get a chance, use a 350 crank.
Also avoid the newer flat tappet cam grinds (xtreme, voodoo, ect). They tend to go flat quickly due to very aggressive cam lobes. The 270H and 280H grinds have been around for a lot of years and are already aggressive enough. And, use diesel engine oil with your new cam, as recommended by compcams if you use flat tappets.