UnBalanced SBM Engine build

OK, a search of FABO shows that everyone recommends a crank balance.
But who has just "thrown together" a 360 Mopar over the past 30 years and never had it balanced?

Well I have. In the early/mid 80s I was young and built my "Good" 360. I used aftermarket pistons (cast) stock rods, std crank/balancer/flexplate/2bbl converter.
I never weighed anything, or balanced anything etc, in fact as I didnt trust "Chevy Shops" I even pressed on the pistons myself...breaking a few ring lands in the process, but...oh well.

Long story short...I put it in a 4 door 68 Valiant, popped in an ST-21, a rubbish Offy 360deg equaflow, 750 vac, 4.1s, 727, stock converter, and use to click of 12.6-12.8 IN FULL street trim...pipes on, retread tyres etc. Fastest mph was 111mph with a borrowed 850 mech.

The engine was a bit buzzy, but never overly, I use to rev to 6500 occasionally, when I put the same engine in my Dart in the mid 90s and installed a worn out 2bbl 360 cam, it was relatively smooth. When I rode in my friends Hot 360 70 Cuda, his engine, to me, vibrated more than my old smogger, and his was balanced blueprinted etc etc.
Now, Ive decided to freshen the old girl up (its only been 30 years:-\"), Im a bit worried about this "Balancing stuff".
Im using some nice polished factory rods, KB190 pistons (both second hand of course), which on my cheap chinese scales, weighs 1490g all up (bearing, pin)
Ive weight some stock 75 360 pistons/rod same, @ 1559g, my old cast combo weighs @ 1565g. I notice a thread on factory weights and a stock 360 piston/rod/pin = 1548g supposedly.

Now as my new piston rod combo is around 70g less than my old 'Overweight" combo, will my engine be seriously underbalanced, or will the lighter new combo not affect much.
As my poor old block at +40 spewed out so much flaky rust that im surprised it has a bore left, I dont want to spend a fortune on balancing, as I may go to a different combo in the future ....maybe.
Im going to use the 272 mopar cam, maybe rev to 6K.

So how many other people have built an unbalanced combo b4, and have you had any problems or not?. thx