You can always submit your measurement after placing the order. For now, just select Customize with Made to Measure, click Add to Shopping Bag and complete order. Later on go to Account section, visit My Orders page and submit your latest measurement.
If your bare chest size measurement is 40 inches, you should select size 40 only from the product page. The "Top Chest" attribute in the size chart refers to the garment's chest size. It is inclusive of the required 3 to 4 inches loosening, to ensure the right fit.
If your bare chest measurement falls between 2 sizes i.e 37 inches, you should select size 38.
https://www.utsavfashion.com/product/woven-art-silk-kurta-jacket-set-in-cream-mgv1643-sh222170288Woven Art Silk Kurta Jacket Set in Creamhttps://medias.utsavfashion.com/media/catalog/product/cache/1/small_image/295x/040ec09b1e35df139433887a97daa66f/w/o/woven-art-silk-kurta-jacket-set-in-cream-v1-mgv1643.jpg96.8121USDInStock/men/men/plus/men/festive/men/art silk/men/white/men/grey/men/kurta pyjama/men/buttons/men/traditional/men/wovenWoven Art Silk Kurta Jacket Set in Cream <ul><li> Art Silk Kurta in Cream</li><li> This Readymade attire is Enhanced with Brooch and Buttons and is Crafted in Chinese Collar Neck and Full Sleeve</li><li> Available with an Art Silk Aligarhi Pant in Cream and an Art Silk Jacquard Nehru Jacket in Grey</li><li> Do note: Footwear shown in the image is for presentation purposes only. Half to one inch may vary in measurement. (Slight variation in actual color vs. image is possible)</li></ul>USDtype_new:Kurta Pyjamacolorfam:White, Greyfabric:Art SilkWhite, GreyArt SilkKurta Pyjama11%-20%MenMore than 15 DaysReadymadeFestiveMenswearButtons, Traditional, Woven34, 36, 38, 40, 4244, 46, 48, 50, 52