KEVIN CONWAY - re: full size car battery in a NF, I "THINK" the battery I use in my #72 is a group #26, there's also a #26R which is the same size but the pos & neg posts are reversed, Here's a battery group size chart I pulled off the 'Net;
http://www.rtpnet.org/teaa/bcigroup.html
Measure the height, width, & depth available on your CC and take your tape measure to the local battery store and measure away. To fit the big battery you probably will have to modify or remove the cross brace in the hood. To fit the big battery AND big gas tank I had to remove the one in the 72. I use the repair clamp-on ends and use the factory battery leads with the ring terminals bolted to the clamp-on end bolts to convert from the battery posts to the factory battery leads. They also make tapping power to run my 12V sprayer a snap too, I just use the other bolts on the clamps for the sprayer leads.
Back in Jan, 1980 when I bought my #72 very well used it came with a dead battery, Dad gave me the old battery out of his '78 Ford Fiesta which fit perfectly with NO changes to the battery box. The #70 Dad did rework the battery box, and it has an even larger battery in it, think it's the same size as ALL full size Ford cars/trucks use, and they're available up to 850 or 1000 CCA.
HARRY - Yes, a full gas tank puts more pressure on the gas at the bottom of the tank, the fuel lines, the main fuel float valve. But while you're out taking pic's of your 169, take the carb apart and look how small the flow orfice is in the main fuel float valve. It's WAY less than 1/16th inch diameter. The gas experiences the same effect water does in a water tower over 100 feet in the air, but in the case of a CC gas tank, the difference in "Head Pressure" is maybe six inches.
The idea a CC/Kohler gas line "HAS" to run uphill is crazy, maybe Kohler/IH did it that way but it's not required, like I said in my last post, it will hold gas in the fuel line and not let it drain down to the carb, but as long as gas is available in the tank, gas will still flow to the carb. Probably a better explaination is that the automatic cut-off machine for the rubber or metal fuel lines had poor dimensional repeatability, so to prevent short fuel lines the supplier made them all slightly longer than needed. Many of the co's I've worked for have had these cut-off machines and they typically can't hold lengths closer than +/- 1/4", but they cut REALLY fast. Plus a longer fuel line allows for the lines to be trimmed, because the ends always deteriorate faster than the middles. And when removing fuel lines for service to the filter or carb, it's often better to cut the fuel line off the hose barb than to try to pry it off, and with the longer fuel line you dont have to replace the line because it's too short.
Plus I highly recommend using SS worm gear hose clamps instead of the little round wire clips or clamps, MUCH less chance of leakage, or a fuel line coming off and pouring raw gas on a hot and running Kohler. I see too many of these old CC's burned up from engine fires which normally start with gas leaks.
And YES WAYNE, a CC will run with the stock fuel lines/filters, etc., but they'll run just as fine and longer between carb cleanings with a better fuel system including additional fuel filtering. The old 5 quart tank & filter I had on the 72 ran for around 20 yrs with only ONE fuel filter cleaning because of water plugging the filter one afternoon while mowing. Tractor ran fine until I was about half done, then stopped just like it ran out of gas, and with the clear glass filter I could see I had plenty of something still in the tank. Turned out it was dirty water filtered out of the gas, shut the fuel off, disconnected the fuel line up stream from the filter, tilted the filter down to drain it out, disassembled the filter, flushed it with gas, reassembled and ran the tractor for another several years till I pulled the engine to install the K321.