The lifters, per most rules for this level of racing, are solid flat tappets.
The most dangerous time in a flat-tappet cam's life is the first few minutes when it's breaking in with the lifters. The high-spring pressures used in racing combined with the aggressive lobe grinds make "wiping" a lobe and ruining the cam a real possibility. To prevent this, you can take a few preventative measures. You should have already liberally coated the cam lobes in assembly lube. Now, after cleaning the lifters, spray the faces with a dry graphite lubricant.
After the graphite has dried, the next step is to apply a lubricant like the white lithium grease you see here or some other thick assembly paste that won't drip off.
Now, as you install the lifters, make sure to coat the lifter bores and the bodies of the lifters with assembly lube as well.
Here's an instance where you always have to be willing to adapt during a build. Even though we had enlarged the pushrod holes, we still had interference problems with the mockup pushrods and the side of the head once the pushrod guides were installed. We've used these Comp Cams guides in several other builds, and they are fine, but they just won't work in this application.
Instead, we had to switch to a set of adjustable guides from Isky. Compared to the Comp guides, the Isky pieces (bottom) are made in two interlocking pieces. They also have larger bolt holes which also provide some adjustability. They are more expensive than the standard plates, but in a situation like this they are a lifesaver.
Here, you can see the guide plates installed on the heads. If you need to move the slots closer together, you can grind the ends of the interlocking tabs. The screw-in rocker studs are from ARP. They should be torqued to 50 pounds with moly lube, unless any of the holes on your head extend into the water jacket, in that case use thread sealer.
Once you've found your correct pushrod length, you can continue to use your pushrod checker to degree in the cam while you wait for your new pushrods to come in. The first step is to find top dead center of the piston in the number-one cylinder (the first one on the right). You can do this with a piston stop screwed into the spark plug hole.