360 magnum. 1 piston lower in cylinder??

A lot of cams, maybe most, IDK, have 4 degrees advance built in at dot to dot., making a 110 cam go in at 106 ......theoretically.
For typical street use;
Flat tappet cams designed for the 904 lifter, have some of the fastest acceleration ramps around, so I wouldn't lose any sleep over not having a roller. And the 1.6 arms by themselves , are also not a big loss. These are minor blips in the big picture that are easily overcome at your power level, just by selecting the right cam. Your crane is already set up to be a torque monster. Here's the rub, If you put a bigger cam in there, as it now stands, your bottom end will get worse. Not might get, but will get. So you need to get to the bottom of why it is so gutless now, and if something is wrong,fix it!
So, the first thing I would do is check that the carb is fully opening with the pedal floored.
Next is to check that cam, for lobes going flat. If the cam is good, then next is a Leakdown test, and after that is a compression test with a known good gauge.
If those give favorable results, I would dig into the ignition-timing, first proving TRUE TDC.
I suspect you are gonna find some issues with these tests... but if not...............
Get some gears in the back, ASAP, and then after you wipe the silly grin off your face..... then you can revisit that stinking convertor.
In post #26 I think I read 2600TC; was that a typo?
A 100rpm is not a big deal, but I gotta wonder if it's working right?

But I'm still going on the assumption that your Crane HV260-2 is a 260 advertised duration cam; I could not find specs on the web.

Here's something to brighten up your day;
A long time ago I had a 270/110 Hughes cam in my 360 with a manual trans, and a starter gear of 9.44.. That hummer would boil the hides right off idle. In fact one of my favorite things to do was,with the line-loc on, break the 295s loose and then idle the engine down to just barely be spinning them; then listen to the tires howl and shriek as they warmed up and began to drag the rpm down...... to which I would respond with just a lil more gaspedal. Fun times.
That 270* is about 1.5 sizes bigger than your 260*, and at 8.5 compression ratio, it would have been awfully soft on the bottom there. So I pumped the chitoutof the compression ratio.
Now consider what 3.55s would do for you in comparison;3.55x2.45=8.70.Looks a lil soft..... until you factor in the TM in the TORQUE convertor, which is supposed to multiply engine torque, when the vehicle is standing still; that is what they do. I have read numbers as high as doubling the engine torque with the vehicle at rest. As the car moves out, the multiplication diminishes but at WOT, it rarely falls below 10 or 5 % multiplication.
Now lets look at this in your car. At rest the TC should double your TM to 8.7x2.0= 17.4! Yikes! But as the car moves out, lets say it falls to plus 8% by 3000rpm/24mph, with an effective ratio now of 8.7x1.08=9.40;
does that number look familiar? Why yes AJ isn't that what you were running in your torque-monster? Why yes Joe, that is correct.
That is what TCs are supposed to do. :)
And here's a lil something to dim the light just a lil.
I suspect your TC ain't doing that :(
Why do I think that? Well, 2.71x2.45x2.0=a tire shredding 13.27 effective ratio; which should bust the tires loose instantly with the torque that is theoretically available at minimum 2500. As soon as the tires spin,the TC backs off, so you gotta have engine-torque to maintain the spin. And at a minimum 2500rpm now, there should be plenty of power to do whatever you want.
I could tell you to pull that TC outta there right now....... BUT;
but for all I know,your engine could be down on power for multiple reasons, and we need to get to the bottom of that first........ cuz if you spend a quarter of your budget on a new TC and nothing changes; you're not gonna like me very much. And I am not well-off enough to pay for that mistake.And I know of no good way to test the TC in-chassis with an unknown engine.
But like I said, your HV260-2 is an unknown to me. If for instance that 260 number had nothing to do with duration,and that cam was really a 292/292/108, then I would tell you exactly what is wrong with your combo.
No laughing matter,lol