Need advice on shish kebab for tomorrow's meal.

You could also do chicken kebabs, but, I’d say a depending on your budget the best beef would be top sirloin or another nicer cut of steak, and the pork could be boneless ribs, yes.

I always use chunks of potato too, you can also add chunks of corn on the cob and whole mushrooms, I have never tried the carrots, I’d think they would be tricky if not sliced thin.

Sounds delicious!

Use a marinated round, and late placement of mushrooms and tomatos with the kabobs.

I made kebabs from the hearts and gizzards of the pheasants I got last season.

I would use the tri-tip or brisket for the beef, loin for the pork, and backstrap or loin for the lamb kebabs. Use cherry tomatoes, mushrooms and large garlic stuffed olives as well as your other vegetables.

What to buy and what to use when it comes to meat for kababs has more to do with your guests as I found it was better to have various types of meat, fish, poultry and veggies.
One of my favorites is boneless fish with a side dish of light soya sauce mixed with a few drops of sesame seed oil and a bit of chili sauce. It works well with chicken or pork although the white meat tends to be best for chicken and pork although that is another personal preference.
When it comes to beef, I prefer thin sliced, rolled up and lightly marinated but use tenderloin if the price isn’t an issue, otherwise rib eye, prime rib or even sirloin lightly seasoned with garlic. Best I ever had was lamb with fresh rosemary, garlic with a side of mint jelly for the English who know when to pass on the HP sauce.

2 Hints that I’ve seen on a few different cooking shows are, always do your vegetables on separate skewers, because veggies cook faster than meat and you don’t want to under cook your meats. Also, whatever you put on your skewers, make sure that there is a tiny bit of room between one chunk to the next, because the middle part of the chunks won’t cook evenly if they’re actually touching.

My cousin threw a kebab barbecue party and what she did was to put out each of the items (beef, chicken chunks, shrimp, vegetables) in separate plastic tupperware containers over ice (so everything would stay fresh and each item would not contaminate or flavor the other items by accident) then she had 3 different types of marinades in separate bowls with a brush for each one (one savory, one spicy and one citrusy). Then she had another large, longish container with her wooden skewers soaking in cold water. Then each guest would take a wet wooden skewer or two (this is so they don’t burn) and go down the line of meats and veggies and put whatever they want on their skewers, then they would brush on whatever marinade they wanted and then lay their skewers onto the barbecues. She actually had 2 big barbecue grills going, so there was plenty of room, and she designated the top section of both barbecues to veggies only (because she had, including myself, several vegetarians, so that was nice to be able to keep it separated) Everybody cooked their own skewers and took them off when they were done. It was really fun.

She also had mushrooms, cherry tomatoes and small sweet peppers.

Stew beef works and is already cut into chunks.

Thanks to all.
It is only seven adults and three young children.
Thanks for the idea of separating the vegetables from the meat skewers, does give the vegetables a chance not to get overcooked,

If my guests will eat lamb and I can find something reasonable I might do that, the beef is the alternative.
I have eight long flat metal skewers that I thought I would stick into the charcoal and let the heat and smoke surround the kebab chunks. Tuna might be a good alternative although all the participants eat meat so I don’t have to worry about a vegetarian.

Chicken might be best for the children.

Thanks to all

Cooking over a grill is usually relatively fast and dry. However, tougher cuts of beef (like round, or stew meat) need long, slow, moist cooking to make them tender and palatable. I would second @Coloma‘s advice about using a more tender cut to start out with, like sirloin, which does fine with the sort of cooking you’re planning to do. Many cuts will be edible, but some are more pleasant to eat than others.