For a "stock" dual port engine, 'bout all I'd do is what you've already done, plus Herb's suggestion of going to the smaller 30-31 carb. You will loose just a little top end power but you WILL get better all around performance. A new one cost about $100 at most swap meets and the adapter will set you back another $10-15. But, after you've spent months trying to get all the flat spots out of a 34 you'll think it's the best $115 you've ever spent. A 30-31 will almost always idle and accelerate smoothly right out of the box! Been there, done that . . . 3 or 4 times! One thing you need to know about the new Brosol (Solex of Brazil) 30-31 is that all of the screws and the idle cut-off solenoid are going to loosen up within a couple of months. Go ahead and tighten 'em up before you bolt it on.
There are all kinds of "bolt on horsepower" gadgets you can bolt to a stock engine (a single progressive carb or dual carbs, ratio rockers, etc.) but from a dependability standpoint it's not a real good idea to try to get more than stock horsepower from a stock engine. The stock crankshaft is not counterweighted and when you try to make too more than stock hp it'll flex and in pretty short order the main bearing saddles will be wallowed out.
To get the illusion of more power (on the bottom end) and possibly a little better handling at the same time, you might want to look into dropping the car an inch or two (dropped spindles on front if it's a standard, Top Line Parts "Adjust-A-Struts" if it's a super, and re-index the rear torsion rods) and go to a low profile tire. I've never done this, but I would think that should give you a stiffer sidewall for better handling and at the same time a smaller tire circumference will change your final drive ratio. I've never went smaller than stock with a tire, but I've put some oversized tires on a Baja before and it felt like it robbed a bunch of hp from the bottom end . . . gas mileage and top speed improved though. I'd guess that going smaller would have the opposite effect . . . less top speed and gas mileage, but better acceleration.
:cool: