Harold, I have a lot of experience with the Fox .35's. I can say with certainty that you could run into some minor problems. I will also add if you can JB weld some brake tubing to the side of the case and leave it flush with the exhaust stack I would go that route. I rough the case up with a Dremel tool and clean it with acetone or thinner prior to using the JB. You can easily clean residual JB weld with standard isopropyl alcohol and a Q-tip if it gets on unwanted surfaces. If this type of fix is unpleasing to you and another case is the option you need to check certain fitments. Crankcases can sometimes vary in nose length and when the prop is tightened down the prop driver can bind on the nose of the case. I experienced this more than once with using newer 50-60th cases when switching my 40th series over to them. Knowing how Fox tolerances can be, I can see similar issues.

        The liner fit to the new case can also prove to be problematic. I've had to lap some liners into the case due to the fit being too tight. When the engine was running and leaning out the engine would sag. However, if it drops right in, this shouldn't be an issue. The other is that you can have 10 conrods and several of them could be a few thou wider than the others. This can proved to be a real headache when trying to get the rod on the crankpin. It's a bit of a trick just getting it on and off on a assembled engine. However, the case internally may also be slightly thick enough which just doesn't allow the conrod to pop onto the pin. A little dusting with a Dremel can remedy this. The next thing that I will mention is the old head to the new case. Fox's can be very cantankerous about tightening the head. You might find that when the head goes on it seems fine, then you snug one of the screws and all of sudden the piston is binding in the liner.

       This is the magic screw, there can be more than one of them. It's important to install the parts dry and glow plug removed and slowly turn the engine over during the head tightening process feeling for binds. I know the later  L&J offered  AAC type piston liners and ABC piston liners and there not easy to find. I do believe the earlier versions were just the stock setups that had surfaces trued up which could make certain installations less of a concern. That being said the new case is a stock Fox case or old Fox case in which the top of the case isn't as true as the L&J version. Tighten all screws in a criss cross fashion slowly easing up on them until snug. Good luck