Baking in gas oven does not brown the top
This is an issue I've had to come to terms with myself. I spent most of my catering life spoilt by having a massive fan assisted electric ovens with space for 24 trays at once. Then one day I left it all behind to work in a tiny 2 chef kitchen where all we had was a bottom heated gas oven. The first 6 months was a nightmare. It's still not easy even to this day but I'll share a couple of tricks me and my colleague have found.

Its all about the airflow:

Forget about the middle shelf for baking it's useless. It's there for roast joints and ... Stuff. Get your baked goods on the top shelf. The reason you are not getting browned tops is all the heat is hitting the bottom of your tray, by the time it reaches the top of your oven and bounces back down to your food it's nowhere near the temperature required.

In order to help cushion the bottoms of your food and direct the heat towards the top, you need to put a tray slightly larger than the tray you are cooking on, on the shelf below. You can add water to this tray for bread and Yorkshire puddings as the steam helps regulate the heat also, but when cooking pastries I find it makes the pastry more likely to split and crack. 

Locate the thermostat in your oven. In ours, it's at the top right, in the middle. Always ensure there is sufficient space around it for the heat to hit it. If it's blocked in any way you'll find the oven just keeps pumping heat out. It'll be 300c at the bottom but the thermostat will still think it 100c. 

Sometimes you will find the tops are now cooking perfectly but the bottoms are a little less done. At that point, you will be safe to either move the food down a shelf to help crisp the bottoms or if making scones you can safely flip them over just to finish off. 

Good luck.