I personally dont think it's worth the effort/money. I'd go with some extra cubes for more torque/horespower than put in longer rods and gain maybe 1 horsepower. I did this on a '74 302 block, the longer 289 rods put the pistons at .005 out of the hole, and compression is around 10.2 with flat-tops. I didnt notice any difference in power at all...in fact I think it lost low-end torque compared to the standard-length rod engine. but that's just my opinion.
If you look at this again you will realize that to put a long rod motor together you need 2 things. #1 a longer rod, that is obvious. #2 the correct compression height piston. Now look at what you need for a stroker shortblock. 3 things. #1 a longer stroke crank, #2 the correct comprssion height piston, #3 the proper rod. So basicly you are only a stroker crank away from a larger engine if building a long rod motor. Now you are willing to pay $860 for a long rod kit. Shop around and you can find 347 kits for $995. So for an extra $135 you can have more cubes and more power. I have done a fair amount of research on the benefits of the long rod combo. What it really boils down to is cylinder wall side load. More side load will need a stonger block, at minimum. In all the information I have found I have yet to see any proof of the long rod making more power. A stroker kit won't make more power, unless you build it in, but will lower the operating range you work in, giving longer engine life. The same goes for the long rod. In a very high rpm application it may make sense to go with a longer rod, but for your average street motor, it will be hard to see or feel the benfits. Some one put it to me this way, use the longest rod possible for the stroke and deck height block you are using. All the info I have found, points to this being the correct way to go.