Always visit the shop that is to do your machine work beforehand and look at the conditions of work in process. Ask what thier processes are for cleanin and rework of the parts.What they are doing on the work at hand is what they will do on your equipment.
Most rebuilders now burn the deposits from engine blocks and heads in a special process oven. They are then pressure washed and are spotless when complete. The old "vat" system will not always remove built up grime, scale and sludge. Talk to the shop about it and get them to clean your parts properly. Don't rant and rave, just discuss the shortcomings and determine between you how they can fix the problem.
The keying slots for the rod bearing inserts must be on the same side. If they are not, the rods are not useable. The markings mean nothing once the rods have been resized. Turning the cap around is asking for a burnt rod bearing, due to misalignment of the big end. Probably only a few thousandths, but the rod clearance is normally around 0.0009 to 0.0015 so a few thousandths will ruin the whole job.
You can check the balancing operation yourself. Weigh each rod/piston assembly and if balanced properly they will be within a gram or two of the same weight. Then each big end can be weighed by holding the piston in a fixed horizontal position and weighing the big end weight on an accurate acale. Anything over a gram or two is too much. To properly balance the assembly, each piston should be made to weigh the same before installing on the rod. The rod ends (All big end weights and all Small end weights) should be the same as well as the overall rod weight. Piston weight is removed from the bosses under the wrist pin and rods are balanced in weight from the pad on both ends.
Don't get discouraged, just keep at it and make sure your work is done right. Then when you assemble the engine, it will stay together. It doesn't take a genius to build and engine, just exacting attention to detail.
Good Luck
