The reason 4230's were mentioned and compared is because YOU brought them into the discussion.
Suggesting that someone tie two R tractors together to farm makes no sense. If a guy wants a project that's fine but the cost/labor involved would be double the price of a nice 100 or even 150 horse tractor.
I care not one bit what kind of tractor this guy gets but hopefully he will realize from this discussion that 200 acres of row crop is beyond the scope of a single two cylinder tractor if he intends to get things done in just a few days.
On a side note, the tandem R's will still never do as much work as a single 4230 with an efficient operator and matched equipment. The 4230 will be headed back down the field with the tandem R's are still turning around. The guy on the 4230 can catch another gear on the headland to buzz on over while the guy in the tandem R's is trying to figure out how in the world he is going to change gears.
On another side note. The tandem R's together may pull more pounds on the drawbar than the sum of two singles but it should with all the added weight of the hitch. They are heavier. The tandem R's however, will never produce more than the sum of their rated HP. They will pull twice their normal load at the same speed or their normal single load at double the speed. Dont forget to deduct HP from the rating to run any hydraulics for the steering. I bet that would eat your spare 6 HP :)
The supposed "magic" of hitching tractors together and "gaining" power is simply a wives tale of the folks selling conversion kits all those years ago. If a single tractor was ballasted to exactly the same weight (properly distributed) as itself plus half the hitch, it would perform half the work of the tandem tractors. There is no magic in physics.
I'll say again that old diesel two cylinders are really neat and had an incredible place in production agriculture 60 years ago but are best suited for plowdays, parades and tractor shows now. Yes, they were fuel efficient but are limited by low pressure hydraulics, marginal charging systems, single speed engines, no rocksaft and limited variation in working speeds.
I'll ride in my soundgard body all day while you ride that really cool tandem R and we'll see who feels most chipper after a 10 hour day and we will also see who plowed the most ground. I know you and I both know the answer to these questions, but I'll never understand your desire to attempt to confuse the younger/less experienced crowd on this board with your HP/torque claims. It's all been spelled out in black and white. It's simple and elementary. It cant be refuted but yet it can be danced around by changing the subject, which is what has happened several times in this discussion.
Just one more visualization in case you honestly are confused (I think you are hard headed, not confused), lets pretend the following scenario. Lets ballast up an R tractor just up to the point that we can power out (choke out the engine) in 1st gear, now lets ballast up the 4230 to the point of being able to power out in A1. After applying all that ballast, lets hitch them drawbar to drawbar. At this point it's all about engine HP since neither tractor can spin out. The R only has 50 engine HP while the 4230 has double that amount. That means the R is going to choke and get dragged backwards. Yes, I realize that you mentioned tandems at several points but you also mentioned that a 75 HP two cylinder diesel could outwork many 100 HP tractors which is why I even entered this discussion. That statement is false and is misleading to a novice. A 75 HP tractor will never ever never be able to produce as much work as a 100 HP tractor. It might weigh more and be capable of pulling a larger plow at a low speed but it will never be capable of as much work in a given period of time. The higer HP tractor might pull a smaller draft load but at a much greater speed which will supersede the lower HP tractor. I think in your mind, more weight and more plow bottoms equals more work, which simply is not true.